CN104201209A - Si/NiO: Ag heterogeneous p-n junction diode - Google Patents

Abstract

The invention discloses a Si/NiO: Ag heterogeneous p-n junction diode. The Si/NiO: Ag heterogeneous p-n junction diode at least comprises a p-n junction and an ohm contact electrode, wherein the p-n junction is a heterogeneous p-n junction formed by a p type NiO: Ag film generating on an n type Si substrate. According to the Si/NiO: Ag heterogeneous p-n junction diode, the p type NiO: Ag film is prepared on the n type Si substrate by the magnetron sputtering process, and then an electrode is manufactured on the p-n junction by the magnetron sputtering method or the thermal evaporation method; the heterogeneous p-n junction diode has relatively high reverse breakdown pressure and large positive current density; in addition, the preparation method is simple in process and small in cost.

Description

A sort of Si/NiO:Ag heterogeneous pn junction diode

technical field

The invention relates to a Si/NiO:Ag heterogeneous pn junction diode. The invention belongs to the field of functional materials and optoelectronic devices.

Background technique

The internal degrees of freedom of the d(f) electrons contained in the strongly correlated material NiO, such as the interaction between spin, charge, and orbit, make NiO exhibit many exotic properties, and at the same time make the physical properties of the material vary with internal parameters such as temperature , pressure, and doping changes significantly. So far, NiO has been used in the research of catalysts, battery electrodes, electrochemical capacitors and other fields because of its good catalytic performance and thermal sensitivity, but there are few reports on its photoelectric properties. Semiconductor heterojunctions are easy to realize the separation of photogenerated charges and are widely used in the research and development of optoelectronic devices such as thin-film batteries. In addition to the above properties, NiO is also a p-type direct wide band gap semitransparent semiconductor material, and its quantum efficiency is relatively high compared with indirect band gap semiconductor materials. At room temperature, the band gap is 3.0-4.0eV, and the d-d orbital transition of the 3d electronic structure makes it have weak absorption in the visible light region. We investigate novel optoelectronic devices via a NiO-based heterojunction format. P.Puspharajha et al used the spray pyrolysis method to make the NiO film transmittance in the visible light band reach 90% by doping Li+ into NiO, and the sheet resistance dropped to 1Ω cm (see literature P PUSPHARAJAH, S RADHAKRISHNA, A K AROF. Transparent conducting lithium-doped nickel oxide thin films by spray pyrolysis technique. Journal of Materials Science, 1997, 32(11): 3001-3006). But in the long run, Ag metal is more common. We introduce Ag element into NiO to prepare NiO:Ag-based heterojunction, which is very in line with the purpose of green energy adhering to modern society. Here we choose the cheap n-type Si substrate as the other end of the heterojunction to realize Si /NiO:Ag heterogeneous pn junction diode. This choice is of great significance for the development of new devices, but there is no report for Si/NiO:Ag heterojunction.

Contents of the invention

In order to improve the performance of the traditional planar pn junction diode, the present invention provides a Si/NiO:Ag heterogeneous pn junction diode, and the prepared Si/NiO:Ag heterogeneous pn junction diode has higher reverse breakdown voltage and large forward current density. Compared with the traditional planar pn junction diode, the rectification characteristic of the novel diode has been improved.

The technical solution of the present invention: Si/NiO:Ag heterogeneous pn junction diode, at least includes a pn junction and an ohmic contact electrode, and the pn junction is a heterogeneous pn junction formed of p-type NiO:Ag and n-type Si.

The preparation method of the above-mentioned Si/NiO:Ag heterogeneous pn junction diode: prepare NiO:Ag thin film on Si substrate by magnetron sputtering process to form heterogeneous pn junction; Electrode; wherein, NiO:Ag and Si surface sputtering or evaporation of silver or nickel or aluminum or gold electrodes.

The invention adopts a NiO:Ag2O ceramic target with a diameter of 50mm, and a NiO:Ag thin film prepared by magnetron sputtering. The background vacuum of the chamber before sputtering is better than 3x10-4Pa, and the relative oxygen partial pressure O2/(O2+Ar)=0%-100% is used here. The sputtering pressure is 0.5-2Pa, and the sputtering power is 100-200W. Before coating, pre-sputter for 5 min to remove impurities on the target surface. The coating time is 20-120min, the substrate temperature is RT-600°C or the post-annealing temperature is from 200°C to 700°C for 0.5 to 1 hour.

The invention utilizes p-type NiO:Ag thin film and n-type Si thin film to form heterogeneous pn junction diode. Through the control of conditions such as NiO:Ag thin films and the optimization of the pn junction structure, the performance of the heterogeneous pn junction has been improved, and the unique advantages of semiconductor NiO:Ag in the application of heterogeneous pn junctions have been fully utilized.

Description of drawings

Fig. 1 is a structural diagram of the present invention

Fig. 2 is the XRD diffraction pattern of the Si/NiO:Ag heterogeneous pn junction diode deposited at a substrate temperature of 400°C in the present invention (Example 1)

Fig. 3 is the I-V curve (embodiment 1) reflecting heterojunction rectification characteristic of the present invention

Fig. 4 is the I-V curve (embodiment 2) reflecting heterojunction rectification characteristic of the present invention

Fig. 5 is an I-V curve reflecting the rectification characteristics of the heterojunction according to the present invention (embodiment 3).

Detailed ways

The Si/NiO:Ag heterogeneous pn junction diode of the present invention at least includes a pn junction and an ohmic contact electrode, and the pn junction is formed by directly depositing NiO:Ag on an n-type Si substrate to form a heterogeneous pn junction. The structure diagram is shown in Figure 1, and its specific preparation steps are as follows:

(1) Use the cleaning method in the semiconductor process to clean the silicon wafer and dry it with nitrogen;

(2) Preparation of p-NiO:Ag: The background vacuum of the chamber before sputtering is better than 3x10-4Pa, the relative oxygen partial pressure O2/(O2+Ar)=0%-100%, and the sputtering pressure 0.5-2Pa, sputtering power 100-200W. Before coating, pre-sputter for 5 min to remove impurities on the target surface. The coating time is 20-120 minutes, the substrate temperature is RT-600° C. and the temperature is 200° C. to 700° C. and annealed for 0.5 to 1 hour.

(3) Electrode preparation: use methods such as sputtering or thermal evaporation (such as: Tang Weizhong, Principles, Technology and Application of Thin Film Material Preparation, Metallurgical Industry Press, 1998 first edition) to make silver/nickel on the surface of NiO:Ag and Si / aluminum / gold electrodes.

(4) Keithley for testing The 2612A detects the ohmic contact characteristics of electrodes and the I-V characteristics (rectification characteristics) of heterogeneous pn junction diodes.

Embodiment one

(1) Use the cleaning method in the semiconductor process to clean the silicon wafer and dry it with nitrogen;

(2) Preparation of p-NiO:Ag: A NiO:Ag ₂ O ceramic target with a diameter of 50 mm was used. NiO:Ag films prepared by magnetron sputtering. The background vacuum of the chamber before sputtering is better than 3x10-4Pa, and pure argon sputtering is used. The sputtering pressure is 2Pa, and the sputtering power is 150W. Before coating, pre-sputter for 5 min to remove impurities on the target surface. The coating time is 40min, and the substrate temperature is 400°C. The XRD diffraction pattern of this sample is shown in Figure 2. It can be seen that the NiO:Ag diffraction peaks and the diffraction peaks of the Ag electrode and the Si sink bottom, and no other diffraction peaks appear;

(3) Electrode preparation: Ag electrodes were fabricated on the edges of NiO:Ag and Si surfaces by magnetron sputtering;

(4) Test Keithley 2612A to detect the ohmic contact characteristics of the electrode and the I-V characteristics (rectification characteristics) of the heterogeneous pn junction diode, see Figure 3.

Embodiment two

(1) Use the cleaning method in the semiconductor process to clean the silicon wafer and dry it with nitrogen;

(2) Preparation of p-NiO:Ag: A NiO:Ag ₂ O ceramic target with a diameter of 50 mm was used. NiO:Ag films prepared by magnetron sputtering. The background vacuum of the chamber before sputtering is better than 3x10-4Pa, and pure argon sputtering is used. The sputtering pressure is 2Pa, and the sputtering power is 150W. Before coating, pre-sputter for 5 min to remove impurities on the target surface. The coating time is 40min, and the substrate temperature is 200°C;

(3) Electrode preparation: Ag electrodes were fabricated on the edges of NiO:Ag and Si surfaces by magnetron sputtering;

(4) Test Keithley 2612A to detect the ohmic contact characteristics of the electrodes and the I-V characteristics (rectification characteristics) of heterogeneous pn junction diodes, see Figure 4.

Embodiment three

(1) Use the cleaning method in the semiconductor process to clean the silicon wafer and dry it with nitrogen;

(2) Preparation of p-NiO:Ag: A NiO:Ag ₂ O ceramic target with a diameter of 50 mm was used. NiO:Ag films prepared by magnetron sputtering. The background vacuum of the chamber before sputtering is better than 3x10-4Pa, and pure argon sputtering is used. The sputtering pressure is 2Pa, and the sputtering power is 150W. Before coating, pre-sputter for 5 min to remove impurities on the target surface. The coating time is 40min, and the substrate temperature is room temperature;

(3) Electrode preparation: Ag electrodes were fabricated on the edges of NiO:Ag and Si surfaces by magnetron sputtering;

(4) Keithley 2612A is used for the test to detect that the electrode contact is ohmic contact characteristic. And the I-V characteristics (rectification characteristics) of heterogeneous pn junction diodes are shown in Figure 5.

Claims (8)

1. A Si/NiO:Ag heterogeneous pn junction diode, comprising at least a pn junction and an ohmic contact electrode, is characterized in that: the pn junction is a heterogeneous structure obtained by growing NiO:Ag thin film on an n-type Si substrate pn junction. 2. The method for preparing Si/NiO:Ag heterogeneous pn junction diode according to claim 1, characterized in that: NiO:Ag thin film is prepared on n-type Si substrate by magnetron sputtering process to form heterogeneous pn junction. 3. The preparation method according to claim 2, characterized in that: the present invention adopts NiO:Ag ₂ O ceramic target, magnetron sputtering process to prepare NiO:Ag thin film, adopt oxygen partial pressure O ₂ /(O ₂ +Ar)=0%-100%. 4. The background vacuum of the chamber before sputtering is better than 3x10 ^-4 Pa, the sputtering pressure is 0.5-2Pa, and the sputtering power is 100-200W. 5. Before coating, pre-sputter for 5 minutes to remove impurities on the target surface. 6. The coating time is 20-120min, and the substrate temperature is changed from RT to 600 ^o C. 7. The method for preparing a Si/NiO:Ag heterogeneous pn junction diode according to claim 1, 2 or 3, characterized in that: the heterojunction is annealed from 200 ^o C to 700 ^o C for 0.5 to 1 hour. 8. the preparation method of n-Si/p-NiO:Ag heterogeneous pn junction diode described in claim 1 or 2 or 3, is characterized in that: adopt sputtering method or thermal evaporation method to make electrode on pn junction; Wherein, Nickel, silver, aluminum or gold electrodes deposited on NiO:Ag and Si surfaces.