CN103489972A - LED structure resistant to electrostatic breakdown - Google Patents

Abstract

The present invention designs an anti-static breakdown LED structure, which can realize the formation of a built-in diode structure at the weak position of the material through the growth of the material, forming a function similar to that of a capacitor and a Zener diode, in the case of an instantaneous large current impact , which can quickly spread the current, thereby ensuring that the basic structure is not damaged. The anti-static breakdown LED structure includes an N-GaN layer, an MQW layer, and a P-GaN layer grown sequentially on the substrate material, and is characterized in that a layer of n-type InxAlyGa1-x is also grown on the P-GaN layer -yN material, or n-type InxAlyGa1-x-yN and p-type InxAlyGa1-x-yN materials are overlapped and grown; wherein, 0.15≧x≧0, 0.25≧y≧0.

Description

A LED structure against electrostatic breakdown

technical field

The invention belongs to the technical field of photoelectric materials and devices, and in particular relates to a structural design of an LED element itself.

Background technique

The GaN-based LED structure is a wide bandgap material with high resistivity. The induced charge generated by static electricity during the production process of this type of chip is not easy to disappear, and when it accumulates to a considerable extent, it can generate a high electrostatic voltage. When the withstand capacity of the material is exceeded, a breakdown phenomenon occurs and discharge occurs. The positive and negative electrodes of the LED chip on the sapphire substrate are located on the chip, and the spacing is very small; for the InGaN/AlGaN/GaN double heterojunction, the InGaN active layer is only tens of nanometers, the ability to withstand static electricity is very small, and it is very easy to be damaged. Electrostatic breakdown causes the device to fail. Compared with traditional LEDs, GaN-based LEDs have a distinct disadvantage of poor antistatic ability, and the failure caused by static electricity has become a very difficult problem that affects the product qualification rate and application promotion.

In order to enable the industrial production of GaN-based LEDs to enter the field of mass production as soon as possible, it is imperative to improve their antistatic performance.

Chinese patent 201994295U mentions a high antistatic LED chip design, by electrically connecting a Zener tube between the first solder joint and the second solder joint, that is, connecting the Zener tube in parallel at both ends of the LED chip, and passing the Zener tube. The tube absorbs the impact of electrostatic high voltage, so as to achieve the purpose of protecting the LED chip, but this solution requires an additional Zener tube, which leads to an increase in cost.

Chinese patent 101335313 mentions a method of improving the antistatic ability of gallium nitride-based LEDs, which inserts an undoped gallium nitride layer into the nGaN layer of the original gallium nitride-based LED structure, or inserts an undoped gallium nitride layer between the nGaN layer and the An undoped gallium nitride layer is added between the potential barrier layers of the multilayer quantum well, so that a capacitance is added to the original gallium nitride-based LED structure, thereby improving the antistatic ability of the gallium nitride-based LED. Due to the n-type defects of the GaN material itself, it is difficult to form an internal capacitive effect through the insertion of a non-doped layer, so the effects of current buffering and antistatic improvement are not obvious;

Chinese patent 101071836 mentions an epitaxial wafer growth method to improve the antistatic ability of gallium nitride-based LED chips, forming a current release channel in the pGaN layer, and performing a cooling and heating annealing treatment on the grown epitaxial film to eliminate part of the accumulated stress , improving the crystal quality of the pGaN epitaxial layer, thus improving the ESD resistance of GaN-based LED chips. However, due to the high resistance and high dislocation density of pGaN itself, its internal current dispersion effect is not obvious, so this design has no obvious effect on improving the antistatic performance of LEDs;

At present, the mainstream technical idea is still to improve the quality of each functional layer: such as uGaN/nGaN/MQW and pGaN crystal to reduce dislocation defects and improve the antistatic ability of the device.

Contents of the invention

The invention designs a new type of LED element, which can realize the formation of a built-in diode structure at the weak position of the material through the growth of the material, forming a function similar to that of a capacitor and a Zener diode, and can quickly The diffusion current ensures that the basic structure is not damaged.

Technical scheme of the present invention is as follows:

The anti-static breakdown LED structure includes an nGaN layer, an MQW layer, and a pGaN layer grown sequentially on a substrate material, and is characterized in that a layer of n-type InxAlyGa1-x-yN material is grown on the pGaN layer, or N-type InxAlyGa1-x-yN and p-type InxAlyGa1-x-yN materials are overlapped and grown; wherein, 0.15≧x≧0, 0.25≧y≧0.

Based on above-mentioned basic scheme, the present invention further does following optimization design:

Before growing the n-type InxAlyGa1-x-yN material on the pGaN layer, a layer of non-doped InxAlyGa1-x-yN material can also be grown with a thickness of 0-50nm. Among them, 0.15≧x≧0, 0.25≧y≧0.

The thicknesses of the above n-type InxAlyGa1-x-yN and p-type InxAlyGa1-x-yN are both 1nm-50nm.

For growing overlapping structures of n-type InxAlyGa1-x-yN and p-type InxAlyGa1-x-yN, the repetition period is 1-5.

The topmost layer of the LED structure is provided with a layer of contact layer for forming better ohmic contact with the electrodes.

The present invention has the following advantages:

The present invention can obviously improve the antistatic performance of LED through the built-in diode structure formed on pGaN, the original antistatic ability of LED HMM2000V passing rate is increased from 80% to 90%, and the average antistatic ability <2500V is improved to nearly 4000V.

Description of drawings

Figure 1 shows a conventional LED structure (and its equivalent circuit components).

Fig. 2 is an LED structure (and its equivalent circuit elements) with only n-type InAlGaN added according to the present invention.

Fig. 3 is an LED structure (and its equivalent circuit elements) with alternating layers of n-type InxAlyGa1-x-yN and p-type InxAlyGa1-x-yN materials added according to the present invention.

Figure 4 shows the LED structure (and its equivalent circuit components) with an additional layer of n-type InxAlyGa1-x-yN on the basis of Figure 3 .

Detailed ways

As shown in the figure, the present invention continues to grow the n-type InxAlyGa1-x-yN material (Figure 2) after the growth of the p-type layer of the traditional LED structure is completed, or n-type InxAlyGa1-x-yN and p-type InxAlyGa1-x- The overlapping structure of yN (Fig. 3). Among them, 0.15≧x≧0, 0.25≧y≧0.

Before growing the n-type InxAlyGa1-x-yN material after the p-type layer, a layer of non-doped InxAlyGa1-x-yN material can be grown, with a thickness of 0-50 nm. Among them, 0.15≧x≧0,0.25≧y≧0;

For the LED structures shown in FIG. 2 , FIG. 3 , and FIG. 4 , the thickness of n-type InxAlyGa1-x-yN and p-type InxAlyGa1-x-yN is preferably between 1 nm and 50 nm.

For the overlapping structure of n-type InxAlyGa1-x-yN and p-type InxAlyGa1-x-yN, the repetition period is 1-5.

After the growth of the above structures is completed, a contact layer can be continuously grown to form a better ohmic contact with the electrodes.

Experimentally confirmed:

After adding a layer of 5nm n-type In0.05Al0.1Ga0.85N material on the pGaN of the original LED, the antistatic performance of the LED is improved from 1500V to 2600V; a layer is interspersed between pGaN and n-type In0.05Al0.1Ga0.85N After 2nm non-doped In0.05Al0.1Ga0.85N, the antistatic performance of LED is improved from 2600V to 3100V;

By first growing a layer of 2nm non-doped In0.05Al0.1Ga0.85N on the pGaN of the original LED, and then continuing to grow a layer of 5nm n-type In0.05Al0.1Ga0.85N material, and then adding a layer of 3nm p After the type In0.1Al0.05Ga0.85N material, the antistatic performance of LED is improved from 1500V to more than 4000V.

Claims (5)

1. An anti-static breakdown LED structure, comprising an N-GaN layer, an MQW layer, and a P-GaN layer grown sequentially on a substrate material, characterized in that: a layer of n-type is also grown on the P-GaN layer InxAlyGa1-x-yN material, or n-type InxAlyGa1-x-yN and P-type InxAlyGa1-x-yN materials are overlapped and grown; wherein, 0.15≧x≧0, 0.25≧y≧0. 2. The anti-static breakdown LED structure according to claim 1, characterized in that: before growing the n-type InxAlyGa1-x-yN material on the P-GaN layer, a layer of non-doped InxAlyGa1-x-yN can also be grown Material, thickness 0-50nm. Among them, 0.15≧x≧0, 0.25≧y≧0. 3. The anti-static breakdown LED structure according to claim 1 or 2, characterized in that the thicknesses of the n-type InxAlyGa1-x-yN and the p-type InxAlyGa1-x-yN are both 1nm-50nm. 4. The LED structure against electrostatic breakdown according to claim 3, characterized in that: for the overlapping structure of growing n-type InxAlyGa1-x-yN and p-type InxAlyGa1-x-yN, the repeated period is 1- 5. 5. The anti-static breakdown LED structure according to claim 1, characterized in that: a contact layer is provided on the topmost layer of the LED structure to form a good ohmic contact with the electrodes.

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