CN106531789A - Method for achieving enhanced HEMT through polarity control and enhanced HEMT - Google Patents

Abstract

The invention discloses an enhanced HEMT, comprising a heterostructure mainly composed of first and second semiconductor layers and source, drain and gate electrodes connected to the heterostructure; the source and drain electrodes are formed on the heterostructure The two-dimensional electrons in the gas-electric connection, the gate electrode is distributed between the source and drain electrodes; the constituent materials of the local regions of the first and second semiconductor layers distributed directly below the gate electrode have a set polarity, so that when When zero bias or no bias is applied to the gate electrode, there is no accumulation of two-dimensional electron gas in the local region of the heterostructure directly below the gate electrode, and when the gate electrode voltage is greater than the threshold voltage, it can A two-dimensional electron gas forms in the local region of the underlying heterostructure. The invention also discloses a method for realizing enhanced HEMT through polarity control. The invention has the advantages of simple process, high repeatability, stable and excellent device performance, low cost, easy mass production and the like.

Description

Method for Realizing Enhanced HEMT by Polarity Control and Enhanced HEMT

technical field

The present invention relates to an enhanced HEMT (high electron mobility transistor) device and a preparation method thereof, in particular to a method for realizing an enhanced HEMT device by adjusting the polarity of a semiconductor material grown under a gate electrode and utilizing a change in a polarization electric field , belonging to the field of microelectronic technology.

Background technique

HEMT devices are made by making full use of the two-dimensional electron gas formed by the semiconductor heterostructure (Heterostructure) structure. Compared with III-VI (such as AlGaAs/GaAs HEMT), III-nitride semiconductors are due to piezoelectric polarization And the spontaneous polarization effect, a high-concentration two-dimensional electron gas can be formed in the heterostructure (such as AlGaN/GaN). Therefore, in HEMT devices made of group III nitrides, the barrier layer generally does not need to be doped. At the same time, group III nitrides have the characteristics of large band gap, high saturated electron drift velocity, high critical breakdown electric field and strong radiation resistance, which can meet the requirements of the next generation power electronic system for higher power devices. , higher frequency, smaller volume and higher temperature requirements.

When the existing group III nitride semiconductor HEMT devices are used as high-frequency devices or high-voltage high-power switching devices, especially as power switching devices, the enhancement mode HEMT device is more helpful to improve the system performance than the depletion mode HEMT device. Safety, reduce device loss and simplify circuit design. At present, the main methods for realizing enhanced HEMT include thin barrier layer, concave gate structure, P-type capping layer and F treatment, etc., but these technologies all have deficiencies. For example, the thin barrier layer technology does not need to use an etching process, so the damage caused is small, but due to the thinner barrier layer, the saturation current of the device is smaller. For another example, F plasma treatment can also realize an enhanced HEMT device, and does not require etching, but F plasma will also etch the barrier layer during the implantation process, resulting in a decrease in device performance.

Therefore, the industry urgently needs to develop an implementation method of an enhanced HEMT device that is easy to implement, has good repeatability, and can effectively guarantee device performance.

Contents of the invention

Aiming at the deficiencies of the prior art, the main purpose of the present invention is to provide a method for realizing an enhanced HEMT through polarity control and the enhanced HEMT.

In order to realize the aforementioned object of the invention, the technical solutions adopted in the present invention include:

In some embodiments, an enhanced HEMT is provided, comprising: a heterostructure mainly composed of a first semiconductor layer as a channel layer and a second semiconductor layer as a barrier layer, and, with the heterostructure Connected source, drain, and gate electrodes; the source and drain electrodes are electrically connected through two-dimensional electrons formed in the heterogeneous structure, and the gate electrodes are distributed between the source and drain electrodes; The constituent materials of the partial region of the first semiconductor layer below and the constituent materials of the partial region of the second semiconductor layer all have a set polarity, so that when zero bias voltage or no bias voltage is applied to the gate electrode, There is no accumulation of two-dimensional electron gas in the local region of the heterostructure directly below the gate electrode, and when the voltage of the gate electrode is greater than the threshold voltage, a two-dimensional electron gas can be formed in the local region of the heterostructure directly below the gate electrode. Dimensional electron gas.

In some embodiments, the polarities of the constituent materials of the partial regions of the first semiconductor layer and the constituent materials of the partial regions of the second semiconductor layer distributed directly under the gate electrode are the same as those of the constituent materials and the constituent materials of the remaining regions in the first semiconductor layer. The polarity of the constituent materials of the remaining regions within the second semiconductor layer is reversed.

In some embodiments there is provided a method of implementing an enhanced HEMT through polarity control, comprising:

A heterostructure mainly composed of a first semiconductor layer as a channel layer and a second semiconductor layer as a barrier layer is sequentially grown on the substrate, and the local area of the first semiconductor layer distributed directly under the gate electrode is made Both the constituent material and the constituent material of the partial region of the second semiconductor layer have a set polarity, so that when zero bias voltage or no bias voltage is applied to the gate electrode, the heterostructure directly below the gate electrode There is no accumulation of two-dimensional electron gas in the local area, and when the voltage of the gate electrode is greater than the threshold voltage, two-dimensional electron gas can be formed in the local area of the heterostructure directly below the gate electrode;

And, making source, drain, and gate electrodes, and enabling the source and drain electrodes to be electrically connected through the two-dimensional electron gas formed in the heterostructure, and distributing the gate electrodes between the source and drain electrodes .

Compared with the prior art, the advantages of the present invention include: an enhanced HEMT device (such as an enhanced GaN-based HEMT device) is realized by controlling the polarity of the material during the material growth process, preferably, wherein the control of the polarity of the material It is realized by patterning the substrate, which can effectively ensure the crystal quality of the material at the heterostructure, so that the overall performance of the device is not or slightly affected, and in the process of realizing the enhanced HEMT Etching without introducing plasma reduces device damage, and has the characteristics of simple process, high repeatability, low cost, and easy mass production.

Description of drawings

Figure 1 is a schematic diagram of the local structure of a common depletion-mode GaN HEMT device;

Figure 2 is a schematic diagram of a local structure of a common enhancement mode GaN HEMT device;

Fig. 3 is a schematic structural diagram of a typical implementation of the present invention using polarity control to realize enhanced HEMT;

Fig. 4 is a schematic structural diagram of a typical embodiment of the present invention adopting polarity control to realize enhanced MISHEMT;

Fig. 5 is a schematic diagram of the energy band of an enhanced HEMT realized by using polarity control in a typical embodiment of the present invention;

Description of reference numerals: substrate 1, gallium nitride 2, aluminum nitride 3, barrier layer 4, source electrode 5, drain electrode 6, two-dimensional electron gas 7, gate electrode 8, seed layer 9, nitrogen polar region 10. Gate dielectric 11.

detailed description

The technical solution of the present invention will be explained in more detail below. However, it should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described in the following (such as embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, we will not repeat them here.

One aspect of the invention relates to an enhanced HEMT. In some embodiments, the enhanced HEMT includes: a heterostructure mainly composed of a first semiconductor layer serving as a channel layer and a second semiconductor layer serving as a barrier layer, and a Source, drain, and gate electrodes; the source and drain electrodes are electrically connected through two-dimensional electrons formed in the heterostructure, and the gate electrode is distributed between the source and drain electrodes. Wherein, the constituent materials of the partial region of the first semiconductor layer and the constituent materials of the partial region of the second semiconductor layer distributed directly under the gate electrode all have a set polarity, so that when zero bias is applied to the gate electrode or there is no When a bias voltage is applied, there is no accumulation of two-dimensional electron gas in the local region of the heterostructure directly below the gate electrode, and when the voltage of the gate electrode is greater than the threshold voltage, the heterostructure directly below the gate electrode can A two-dimensional electron gas is formed in the local region of the material structure.

It should be noted that the aforementioned "below the gate electrode" mainly refers to the area covered by the orthographic projection of the gate electrode on the heterostructure.

In some embodiments, the polarities of the constituent materials of the partial regions of the first semiconductor layer and the constituent materials of the partial regions of the second semiconductor layer distributed directly under the gate electrode are the same as those of the constituent materials and the constituent materials of the remaining regions in the first semiconductor layer. The polarity of the constituent materials of the remaining regions within the second semiconductor layer is reversed.

In some embodiments, a gate dielectric layer is distributed between the gate electrode and the heterostructure, that is, an enhanced MIS (metal-insulator-semiconductor) HEMT structure is formed.

In some more specific embodiments, the enhanced HEMT may include: a heterostructure mainly composed of a GaN layer and an _{AlxGa (1-x)} N (0<x≤1) layer, and, with the The source, drain, and gate electrodes connected by the heterostructure; the source and drain electrodes are distributed on the _{AlxGa (1-x)} N layer, and are electrically connected through the two-dimensional electron gas formed in the heterostructure, and the gate electrode It is arranged between the source and drain electrodes; the constituent materials of the local area of the GaN layer distributed directly below the gate electrode and the constituent materials of the local area of the Al _x Ga _(1-x) N layer are all N polarized materials, and The constituent materials of the remaining regions in the GaN layer and the constituent materials of the remaining regions in the Al _x Ga _(1-x) N layer are all Ga polarized materials.

In some embodiments, the source and drain electrodes are located on the surface of the _{AlxGa (1-x)} N layer and are electrically connected to the two-dimensional electrons through an ohmic contact.

In some embodiments, the polarity of the semiconductor material distributed under the gate electrode (especially the semiconductor material constituting the heterostructure) is opposite to the polarity of the semiconductor material distributed in regions other than under the gate electrode.

In some embodiments, when the gate electrode is at zero bias, the polarity of the material under the HEMT gate is nitrogen polarity, the two-dimensional electron gas cannot be formed, and the device is in an off state. When the voltage is high, the HEMT accumulates electrons at the lower end of the gate electrode, and the device is in an on state.

In some embodiments, when the HEMT is working, the source electrode and the drain electrode are respectively connected to the low potential and the high potential of the power supply.

In some embodiments, an insertion layer or the like may be provided between the first and second semiconductor layers forming the heterostructure, and its material may be AlN, etc., but not limited thereto.

In some more typical specific embodiments, the heterostructure of an enhanced HEMT is mainly composed of GaN/Al _x Ga _(1-x) N (0<x≤1), and the source and drain electrodes are located on Al _x Ga _{( 1-x)} The N surface is connected to the two-dimensional electron gas phase through an ohmic contact, the gate electrode is arranged between the source and drain electrodes, and the GaN and Al _x Ga _(1-x) N materials below the gate electrode are N-face materials, In this area, due to the change of the polarity of the material, the direction of the polarization electric field generated inside the material changes, and the accumulation of electrons cannot be formed at the heterostructure, while in the area outside the gate electrode, the material is gallium polarized, Therefore, a two-dimensional electron gas will be generated at the interface of the heterostructure. Therefore, it is possible to realize that the HEMT device is in an off state when the gate bias voltage is zero, thereby achieving the transition from a normally-on HEMT device to a normally-off HEMT device.

The aforementioned GaN/ _{AlxGa (1-x)} N (0<x≤1) heterojunction structure can also be replaced by a heterostructure such as GaN/InAlN, or other suitable heterostructures known in the industry.

An aspect of the present invention also provides a method for realizing an enhanced HEMT through polarity control. In some embodiments, the method includes:

A heterostructure mainly composed of a first semiconductor layer as a channel layer and a second semiconductor layer as a barrier layer is sequentially grown on the substrate, and the local area of the first semiconductor layer distributed directly under the gate electrode is made Both the constituent material and the constituent material of the partial region of the second semiconductor layer have a set polarity, so that when zero bias voltage or no bias voltage is applied to the gate electrode, the heterostructure directly below the gate electrode There is no accumulation of two-dimensional electron gas in the local area, and when the voltage of the gate electrode is greater than the threshold voltage, two-dimensional electron gas can be formed in the local area of the heterostructure directly below the gate electrode;

And, making source, drain, and gate electrodes, and enabling the source and drain electrodes to be electrically connected through the two-dimensional electron gas formed in the heterostructure, and distributing the gate electrodes between the source and drain electrodes .

In some embodiments, for the control of the polarity of the semiconductor material, it is possible to grow a nanometer-scale seed layer (thickness is about several nanometers to hundreds of nanometers) on the substrate, but not limited to, the material can be selected but not limited to nitrogen Gallium nitride, aluminum nitride and other semiconductor materials can effectively change the growth polarity of the growth material), and then etch the seed layer in some areas by patterning to realize the area with the seed layer and the area without the seed layer Polarity transition during growth of material.

In some embodiments, the method may specifically include:

A seed layer is provided on the substrate, and the seed layer is patterned, and the area where the patterned seed layer is located or the area where the substrate is exposed from the seed layer is located corresponds to the distribution area of the gate electrode,

The first semiconductor layer and the second semiconductor layer are grown sequentially on the patterned seed layer and the substrate surface exposed from the patterned seed layer, wherein the semiconductor material grown on the seed layer and the semiconductor material directly grown on the substrate surface opposite polarity.

In some more specific implementation cases, the constituent material of the seed layer is a nitrogenous material, and the material grown on the surface of the patterned seed layer is a nitrogenous material, and the orthographic projection of the gate electrode on the substrate covers the patterned seed layer.

Wherein, the material of the seed layer can be selected but not limited to gallium nitride, aluminum nitride and other semiconductor materials.

In some embodiments, the growth method of the seed layer can be selected but not limited to metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE) or magnetron sputtering.

In some embodiments, a gate dielectric layer is disposed between the heterostructure and the gate electrode. The material of the gate dielectric layer can be selected but not limited to Al ₂ O ₃ , silicon nitride, SiO ₂ and other semiconductor media.

By controlling the polarity of the material during the growth process of the semiconductor material, the invention can effectively realize the enhanced HEMT device, without introducing damage to the material such as plasma, thus ensuring the performance of the device, and has the advantages of simple process and high repeatability , low cost, easy to carry out large-scale production and so on.

The technical solution of the present invention will be further explained below in conjunction with the drawings and the like.

Referring to FIG. 1, for a common HEMT device (taking AlGaN/GaN devices as an example, hereinafter referred to as "device"), generally speaking, when zero bias voltage or no bias voltage is applied to the gate electrode 8, the drain electrode 6 and the source The electrodes 5 are all connected to the two-dimensional electron gas 7, so the drain electrode 6 and the source electrode 5 of the device are conductive, and the device is in an open state. Generally, this device is called a depletion HEMT device, and it can also be called normally open. type HEMT devices. In the process of turning off the device, a certain negative bias must be applied to the gate electrode, and the applied bias voltage V<Vth will deplete the two-dimensional electrons under the gate. In the actual application process, there are high power consumption and safety aspects. The problem.

Referring to Fig. 2, for a common enhancement mode HEMT device, when zero bias voltage or no bias voltage is applied to the gate electrode 8, since the two-dimensional electron gas under the gate electrode 8 is depleted, the source electrode 5 and the drain electrode 6 is in an off state, and this device is generally called an enhanced HEMT device, and it can also be called a normally-off HEMT device. In order to make the device in the open state, electrons must be accumulated at the lower end of the gate electrode to realize the connection between the source electrode 5 and the drain electrode 6. When the gate electrode 8 is biased to Vg>Vth, Vth is the threshold voltage of the device. For The enhanced HEMT device generally has a positive value of Vth and the device is turned on.

Referring to FIG. 3 , it is a schematic structural diagram of an enhanced HEMT realized by using a polarity control method in a typical embodiment of the present invention.

A method for realizing an enhanced HEMT may include: first, growing a seed layer 9 on the substrate 1 to change the polarity of the material. The growth method can be selected but not limited to metal organic chemical vapor deposition (MOCVD), Molecular beam epitaxy (MBE) or magnetron sputtering, etc. Then, by patterning, the seed layer under the gate is etched clean, and the epitaxial growth of the material is carried out. During the epitaxial process, the polarity of the material grown on the seed layer 9 is opposite to that of the material 10 directly grown on the substrate. , so it can be realized that in the gate electrode region, the accumulation of two-dimensional electron gas cannot be formed, and outside the gate electrode region, due to the spontaneous polarization and piezoelectric polarization of the barrier layer 4 and the channel layer, a high concentration of two-dimensional electron gas will be formed electronic gas. When zero bias or no bias is applied to the gate electrode 8, both the drain electrode 6 and the source electrode 5 are connected to the two-dimensional electron gas 7, but there is no accumulation of two-dimensional electron gas under the gate electrode of the device, so the device The drain electrode 6 and the source electrode 5 are disconnected, and the device is in an off state. When the gate voltage is greater than the threshold voltage, the lower end of the gate electrode accumulates electrons to realize the connection between the source electrode 5 and the drain electrode 6, and the device is turned on. Therefore, the device is a normally-off GaN HEMT device.

Referring to Fig. 4 is the schematic diagram that adopts the method for controlling polarity to realize enhanced MISHEMT in a typical embodiment of the present invention; At first, on substrate 1, grow one deck to be used for changing the seed layer 9 of material polarity, growth mode can be selected But not limited to using Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE) or Magnetron Sputtering, etc. Then, the seed layer under the gate is etched clean by a patterning method, and epitaxial growth of the material is performed. Wherein, the patterning method can be implemented by any suitable method known in the industry, such as photolithography, wet or dry etching, and the like. Furthermore, during the epitaxial growth process, the polarity of the semiconductor material grown on the seed layer 9 is opposite to that of the semiconductor material 10 directly grown on the substrate, so it can be realized that the accumulation of two-dimensional electron gas cannot be formed in the gate electrode region, Outside the gate electrode region, due to the spontaneous polarization and piezoelectric polarization of the barrier layer 4 and the channel layer, a high-concentration two-dimensional electron gas is formed. In order to reduce the gate leakage and increase the gate swing, a layer of gate dielectric 11 is inserted between the barrier layer 4 and the gate electrode 8. The material of the gate dielectric can be selected but not limited to semiconductors such as silicon dioxide, silicon nitride and aluminum oxide. .

Referring to Fig. 5, a typical embodiment of the present invention adopts the polarity control to realize the energy band schematic diagram of the enhanced HEMT; it can be obtained from the energy band schematic diagram that the energy band bending of GaN materials with different polarities is opposite, and for gallium surface materials, If the barrier layer is GaN, then there is no electron accumulation at the interface of the heterostructure due to the inability to form a quantum well to confine the two-dimensional electron gas at the interface of the heterostructure. Therefore, the enhanced HEMT device can be realized by different polarization.

Please refer to FIG. 3 for the embodiment. First, a seed layer 9 is grown on the substrate 1. Its material can be selected but not limited to semiconductor materials such as gallium nitride and aluminum nitride. The growth method can be selected but not limited to metal organic chemical vapor deposition. (MOCVD), molecular beam epitaxy (MBE) or magnetron sputtering, etc. The grown seed layer is a nitrogen material. For the aforementioned sample, the material grown above the seed layer is a nitrogen material, and the nitrogen material is covered by the gate electrode. Outside the gate electrode is a gallium semiconductor material. Through epitaxial technology, a channel layer 2, a space layer 3 and a barrier layer 4 are grown on the substrate 1 in sequence. Only the basic structure and epitaxial structure of the HEMT device are shown here. In the actual process of epitaxy and device fabrication, structures such as buffer layer, high-resistance layer, and capping layer are also involved, and methods for forming these structures can be adopted in suitable methods known in the industry. And, in the manufacturing process of the device, the mesa isolation can be carried out first, and the isolation method can be selected but not limited to ion implantation isolation and mesa etching isolation (such as using chlorine plasma), and then through the designed mask and photolithography technology Pattern the source and drain electrodes on the surface of the sample, and then deposit metal, generally choose to deposit multi-layer metals such as titanium/aluminum/nickel/gold (Ti/Al/Ni/Au 20nm/130nm/50nm/150nm), metal deposition Afterwards, the metal outside the source and drain electrodes is peeled off, and rapid annealing (890° C. for 30 seconds) is performed. After annealing, the source electrode 5 and the drain electrode 6 are connected to the two-dimensional electron gas 7 . Then form the pattern of the gate metal by photolithography, deposit the gate metal (generally choose Ni/Au 50nm/150nm) and lift-off process to form the gate electrode, and the gate electrode completely covers the gallium nitride material. In some preferred embodiments, in order to improve the performance of the device, some passivation methods may also be adopted, which are realized through suitable methods known in the industry.

Furthermore, in order to reduce gate leakage and increase gate swing, the present invention is also suitable for manufacturing MISHEMT devices, which can be realized by inserting at least one layer of gate dielectric 11 between the barrier layer 4 and the gate electrode 8 . Wherein, the gate dielectric can be selected from but not limited to semiconductor materials such as silicon dioxide, silicon nitride and aluminum oxide.

The working principle of the HEMT is as follows: Referring to Figure 2, the threshold voltage Vth is a positive value. When the gate voltage Vg<Vth, due to the nitrogen semiconductor material under the gate and the transformation of the polarization electric field, no dual The electron gas is maintained, so the source electrode 5 and the drain electrode 6 are disconnected, so the device is in an off state. When the gate voltage Vg>Vth, the region under the gate will accumulate electrons, and the accumulated electrons will form a new conduction channel, making the source electrode 5 and the drain electrode 6 conduct, and the device is in the on state.

It should be understood that the above-mentioned embodiments are only to illustrate the technical concept and features of the present invention, the purpose of which is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. a kind of enhancement mode HEMT, including：It is main by the first semiconductor layer as channel layer and as the second the half of barrier layer The heterojunction structure of conductor layer composition, and, the source that is connected with the heterojunction structure, leakage, gate electrode；The source, drain electrode lead to The two-dimensional electron gas electrical connection being formed in heterojunction structure is crossed, the gate electrode is distributed between source, drain electrode；It is characterized in that： The group of the regional area of the composition material and the second semiconductor layer of the regional area of the first semiconductor layer being distributed in immediately below gate electrode Setting polarity is respectively provided with into material so that when applying zero-bias or not being biased in the gate electrode, in grid electricity Accumulation without two-dimensional electron gas in heterojunction structure regional area immediately below pole, and work as and be more than threshold voltage in the gate electrode voltage When, two-dimensional electron gas can be formed in the heterojunction structure regional area immediately below the gate electrode.

2. enhancement mode HEMT according to claim 1, it is characterised in that be distributed in immediately below gate electrode the first half and lead The polarity of the composition material of the regional area of the composition material of the regional area of body layer and the second semiconductor layer with the first semiconductor layer The opposite polarity of the composition material in remaining region in the composition material in interior remaining region and the second semiconductor layer.

3. a kind of enhancement mode HEMT, including：Mainly by GaN layer and Al_xGa_(1-x)N shell (0 ＜ x≤1) or InAIN layer group Into heterojunction structure, and, the source that is connected with the heterojunction structure, leakage, gate electrode；The source, drain electrode are distributed in Al_xGa_(1-x)N On layer or InAIN layer, and the two-dimensional electron gas electrical connection by being formed in heterojunction structure, gate electrode is located at source, drain electrode Between；Characterized in that, being distributed in the composition material and Al of the regional area of the GaN layer immediately below gate electrode_xGa_(1-x)N shell or The composition material of the regional area of InAIN layer is N polarization materials, and in the GaN layer composition material in remaining region and The Al_xGa_(1-x)In N shell or InAIN layer, the composition material in remaining region is Ga polarization materials.

4. enhancement mode HEMT according to claim 3, it is characterised in that the source, drain electrode are located at Al_xGa_(1-x)N shell Surface and electrically connected with the two-dimensional electron gas by Ohmic contact.

5. enhancement mode HEMT according to claim 3 or 4, it is characterised in that the gate electrode and the heterojunction structure it Between gate dielectric layer is also distributed with.

6. a kind of method that enhancement mode HEMT is realized by Polarity Control, it is characterised in that include：

Grown on substrate successively and be mainly made up of the first semiconductor layer as channel layer and the second semiconductor layer as barrier layer Heterojunction structure, and the composition material and the second quasiconductor of the regional area for making to be distributed in the first semiconductor layer immediately below gate electrode The composition material of the regional area of layer is respectively provided with setting polarity, so as to work as and apply zero-bias in the gate electrode or not apply During biasing, the accumulation without two-dimensional electron gas in the heterojunction structure regional area immediately below the gate electrode, and when in the grid When electrode voltage is more than threshold voltage, two-dimensional electron gas can be formed in the heterojunction structure regional area immediately below the gate electrode；

And, make source, leakage, gate electrode, and enable the source, drain electrode by be formed in the heterojunction structure two Dimensional electron gas are electrically connected, and the gate electrode is distributed between source, drain electrode.

7. the method for enhancement mode HEMT being realized by Polarity Control according to claim 6, it is characterised in that include：

Seed Layer is set on substrate, and is patterned process to Seed Layer, and make graphical Seed Layer region or from kind The substrate region exposed in sublayer is corresponding with the distributed areas of gate electrode,

Growth regulation semi-conductor layer and the second half successively on the substrate surface exposed in graphical Seed Layer and from graphical Seed Layer Conductor layer, wherein, grows semi-conducting material on the seed layer and the semi-conducting material opposite polarity for being grown directly upon substrate surface.

8. the method for enhancement mode HEMT being realized by Polarity Control according to claim 7, it is characterised in that the Seed Layer Composition material be nitrogen material, and to be grown on the material of graphical seed layer surface be nitrogen material, and gate electrode is on substrate Orthographic projection cover graphics Seed Layer.

9. the method for enhancement mode HEMT being realized by Polarity Control according to any one of claim 6-8, it is characterised in that Also include：Between the heterojunction structure and gate electrode, gate dielectric layer is set.

10. the method for realizing enhancement mode HEMT by Polarity Control according to any one of claim 6-8, its feature exist In the heterojunction structure mainly by GaN layer and Al_xGa_(1-x)N (0 ＜ x≤1) layers or InAIN layer composition, wherein, are distributed in grid The composition material and Al of the regional area of the GaN layer immediately below electrode_xGa_(1-x)The composition material of the regional area of N shell or InAIN layer Material is N polarization materials, and in the GaN layer remaining region composition material and the Al_xGa_(1-x)N shell or InAlN In layer, the composition material in remaining region is Ga polarization materials.