CN103474333A - Doping method for p-type zinc telluride single crystal thin-film material - Google Patents

Abstract

A method for doping a p-type zinc telluride single crystal thin film material, comprising the following steps: Step 1: take a single crystal substrate; Step 2: on the single crystal substrate, epitaxially grow a single crystal thin film; Step 3: in Deposit a layer of _SiO2nanofilm on the surface of the single crystal film; step 4: use the method of dual-energy nitrogen ion implantation to inject nitrogen from the surface of the _SiO2nanofilm downward, and form a p-type under the _SiO2nanofilm Doping the layer to form a sample; step 5: performing rapid thermal annealing on the sample; step 6: removing the SiO ₂ nano film on the surface of the sample to complete the preparation. The invention is compatible with the existing manufacturing process of microelectronic devices and is easy to implement. In addition, the method can also be applied to the p-type doping on the surface of the intrinsic zinc telluride body single crystal, and can be used as a reference for p-type doping experiments of other II-VI group compound semiconductor thin film materials.

Description

Doping method of p-type zinc telluride single crystal thin film material

technical field

The invention belongs to the technical field of semiconductor material preparation, and relates to a doping method of a p-type zinc telluride single crystal thin film material, in particular to a p-type doped zinc telluride single crystal thin film material prepared by using a dual-energy state nitrogen ion implantation method Methods.

Background technique

Zinc telluride is an important II-VI compound semiconductor material with a bandgap width of 2.26eV at room temperature, which belongs to the direct bandgap energy band structure. Zinc telluride has good application prospects in the manufacture of green light-emitting diodes (LEDs), solar cells, terahertz detectors, optical waveguides and other optoelectronic devices. Due to the difficulty in growing zinc telluride bulk single crystal materials, small wafer size and high price, most of the common zinc telluride devices are fabricated on heteroepitaxially grown thin films. At present, the commonly used techniques for preparing zinc telluride single crystal thin films include molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD) and liquid phase epitaxy. The commonly used substrate materials are gallium arsenide (GaAs), Gallium antimonide (GaSb) and zinc telluride (ZnTe) wafers, etc. Intrinsic zinc telluride single crystal or non-intentionally doped zinc telluride single crystal thin film generally exhibits high resistance or weak p-type conduction state, and it is often necessary to make it n-type or p-type with a specific carrier concentration in the device manufacturing process Doping, where the n-type doping elements are chlorine (Cl) or aluminum (Al), and the p-type doping elements are most commonly used nitrogen (N). The specific processes include in-situ doping (MBE, MOCVD), ion implantation and Thermal diffusion of three doping methods. The in-situ doping method is easy to prepare high-quality zinc telluride single crystal thin films with uniform doping concentration, but there is a problem of complicated process control; the ion implantation method has the advantages of precise controllable doping concentration, simple process, and can achieve selective doping However, a certain degree of lattice defects will be generated in the thin film crystal, especially in the surface layer, and rapid thermal annealing must be done to repair the crystal defects and activate the electrical activity of doping elements; the process of thermal diffusion method is very simple, but The doping concentration is not easy to control accurately, and it is also very uneven. Longer high-temperature process time is easy to damage the steep interface of the heterogeneous structure of the device material, and it is only used in individual cases.

Contents of the invention

The purpose of the present invention is to provide a doping method of p-type zinc telluride single crystal thin film material, which is compatible with the existing microelectronic device manufacturing process and is easy to implement. In addition, the method can also be applied to the p-type doping on the surface of the intrinsic zinc telluride body single crystal, and can be used as a reference for p-type doping experiments of other II-VI group compound semiconductor thin film materials.

The invention provides a method for doping a p-type zinc telluride single crystal thin film material, comprising the following steps:

Step 1: Take a single crystal substrate;

Step 2: epitaxially growing a single crystal thin film on a single crystal substrate;

Step 3: depositing a layer of SiO on the surface of the single crystal film _Nano film;

Step 4: using the method of dual-energy nitrogen ion implantation, inject nitrogen element downward from the surface of the _SiO2 nanometer film, and form a p-type doped layer under the _SiO2 nanometer film to form a sample;

Step 5: performing rapid thermal annealing on the sample;

Step 6: remove the SiO ₂ nano film on the surface of the sample to complete the preparation.

The beneficial effect of the present invention is that it is compatible with the existing microelectronic device manufacturing process, is easy to implement, realizes the controllable high-concentration p-type doping of the zinc telluride e single crystal thin film material, and effectively reduces the impact of ion implantation on the surface crystal of the material. The damage of lattice, and the problem of volatilization of tellurium element formed by the decomposition of zinc telluride during thermal annealing is suppressed. In addition, the method can also be applied to the p-type doping on the surface of the intrinsic zinc telluride body single crystal, and can be used as a reference for p-type doping experiments of other II-VI group compound semiconductor thin film materials.

Description of drawings

In order to further illustrate the features and technical solutions of the present invention, the following detailed descriptions are as follows in conjunction with the embodiments and accompanying drawings, wherein:

Process flow diagram of the present invention of Fig. 1;

Fig. 2 is the structural representation of p-type doped zinc telluride single crystal thin film material prepared by nitrogen ion implantation method;

Fig. 3 is the calculation result of simulating dual-energy nitrogen ion implantation with SRIM-2010 software after depositing 80nm SiO ₂ film on the surface of zinc telluride.

Detailed ways

Please refer to Fig. 1 and shown in Fig. 2, the present invention provides a kind of doping method of p-type zinc telluride single crystal thin film material, comprises the following steps:

Step 1: Take a single crystal substrate 10, and the material of the single crystal substrate 10 is ZnTe, GaSb, GaAs or Si wafer. For example: choose the ready-to-use 2-inch semi-insulating GaAs (001) wafer as the substrate material.

Step 2: On the single crystal substrate 10, epitaxially grow a single crystal thin film 11, the single crystal thin film 11 is not intentionally doped, and its thickness is greater than 100nm, and the epitaxial growth single crystal thin film 11 adopts molecular beam epitaxy or metal organic chemical vapor deposition. For example: use molecular beam epitaxy growth equipment to grow zinc telluride single crystal thin film materials heterogeneously. In the experiment, Zn and Te with a purity of 6N (≥99.9999%) were selected as the molecular beam source, and the natural oxidation on the surface of the GaAs substrate was first removed at a substrate temperature of 630-680°C under a background vacuum of better than 10-7Pa. layer, and then epitaxially grow a 30nm zinc telluride low-temperature buffer layer at a substrate temperature of 320°C, and then grow a high-quality zinc telluride single crystal thin film layer at a temperature of 360-380°C. The VI/II ratio of the molecular beam source is controlled between 4.0-6.4, and the thickness of the ZnTe thin film is about 800nm after epitaxial growth for 2 hours.

Step 3: Deposit a layer of SiO2nano _- film 13 on the surface of the single crystal film 11, the thickness of the _SiO2nano- film 13 is 50-100nm, the deposition temperature is room temperature or lower than 200°C; deposit _SiO2nano- film 13 The most common methods are magnetron sputtering, chemical vapor deposition or pulsed laser deposition. For example: use magnetron sputtering equipment to deposit 80nm SiO ₂ nanometer film on the surface of zinc telluride single crystal film at room temperature. The output power of magnetron sputtering is 400W, the background vacuum is about 10-5Torr, the SiO ₂ target is sputtered with Ar+ ions in an oxygen-rich atmosphere, the deposition rate is 0.2nm/s, and the sample temperature is room temperature. In the present invention, the adoption of the _SiO2 nanometer film has not only effectively reduced the damage of the nitrogen ion implantation process to the crystal quality of the zinc telluride film near the surface layer, but also suppressed the impact of the rapid thermal annealing treatment on the decomposition of the zinc _telluride surface layer. The nanometer film then increases the p-type doped hole concentration in the surface layer of the zinc telluride film.

Step 4: Utilize the method of dual-energy nitrogen ion implantation, inject nitrogen element downward from the surface of SiO ₂ nanometer film 13, form p-type doped layer 12 below SiO ₂ nanometer film 13, form sample, described nitrogen ion The implanted energy and dose are 20-30keV, 1.0×10 ¹⁴ -5.0×10 ¹⁴ cm ^-2 in the low energy state, and 60-80keV, 1.0×10 ¹⁵ -5.0×10 ¹⁵ cm ^-2 in the high energy state. The hole concentration range of the p-type doped layer 12 is 1×10 ¹⁸ -1×10 ²⁰ cm ⁻³ . For example: using a domestic LC-4 ion implanter at room temperature from the surface of the SiO ₂ nano film 13 to perform low-energy state 30keV, dose 4×10 ¹⁴ cm ^-2 and high-energy state 70keV, dose 2×10 ¹⁵ cm ^{- 2} nitrogen ion implantation p-type doping experiment. The dual-energy nitrogen ion implantation method overcomes the problem that the dopant element concentration often presents Gaussian distribution and unevenness when the single-energy state implantation is used in the past, significantly improves the uniformity of the dopant element distribution, and increases the precision control of the dopant element The flexibility of depth distribution is conducive to the development of high-performance optoelectronic devices.

Step 5: Perform rapid thermal annealing treatment on the sample, the rapid thermal annealing treatment is annealing in a nitrogen atmosphere with a flow rate of 5-10 sccm at normal pressure, the annealing temperature is 350-500° C., and the annealing time is 1-5 min. For example: use the domestic RTP-500 type rapid thermal annealing furnace, under the protection of atmospheric pressure nitrogen flow rate 5-10sccm atmosphere, do annealing temperature 350-500 ℃ for p-type doped samples, annealing time 1-5min rapid thermal annealing treatment, both It can repair some lattice defects caused by nitrogen ion implantation, and can also activate the electrical activity of doped nitrogen ions.

Step 6: removing the SiO ₂ nanometer film 13 on the surface of the sample to complete the preparation. For example: rinse the above sample with 1:10 diluted hydrofluoric acid aqueous solution for 1-2min, after completely removing the SiO ₂ nano film 13 on the sample surface, a high-quality p-type doped film with a set doping concentration is prepared. Zinc telluride single crystal thin film material.

The hole concentration of the p-type doped ZnTe sample can be measured by the classic Vanderbilt Hall test method. Cut the sample into a square of 8×8mm, test the Hall effect after making an In electrode at the center point of each side, and then calculate the carrier concentration and mobility of the sample, and determine that the type of carrier is electron or voids.

As shown in Figure 3, in order to obtain as uniform a doping concentration distribution as possible in the zinc telluride single crystal thin film material and to achieve the doping concentration set by the process, it is generally necessary to use the classic SRIM-2010 software simulation before the ion implantation experiment Calculation results for ion implantation. Fig. 3 is the calculation result of simulating dual-energy nitrogen ion implantation with SRIM-2010 software after depositing 80nm SiO ₂ film on the surface of zinc telluride. The abscissa in the figure represents the depth distribution from the sample surface in nanometer (nm), and the ordinate represents the concentration of implanted nitrogen element in cm ^-3 . The lower curve corresponds to the nitrogen concentration distribution when the nitrogen ion implantation energy is 30keV and the dose is 4×10 ¹⁴ cm ^-2 , and the middle curve corresponds to the nitrogen concentration distribution when the nitrogen ion implantation energy is 70keV and the dose is 2×10 ¹⁵ cm ^-2 ; The upper curve is the result of the total nitrogen concentration distribution after they are superimposed, which can accurately control the depth distribution of doped nitrogen and solve the problem of doping uniformity.

In the present invention, the non-intentionally doped ZnTe single-crystal thin film sample grown epitaxially and the sample without annealing treatment after ion implantation both present a high-resistance state, and the hole concentration is only on the order of 1010cm ^-3 . After annealing, the hole concentration of the sample can reach 1×10 ¹⁸ -1×10 ²⁰ cm ^-3 , showing a low resistance state. According to the energy and dose of nitrogen ion implantation, as well as the temperature and time of rapid thermal annealing, the thickness and hole concentration of the p-type doped ZnTe single crystal thin film layer can be precisely regulated, which has broad application in the development of ZnTe-based optoelectronic devices. application prospects.

The above is only a specific implementation mode in the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technology can easily think of changes or replacements within the technical scope disclosed in the present invention. All should be covered within the scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (8)

1. the doping method of a p-type zinc telluridse monocrystal thin films material, comprise the steps:

Step 1: get a single crystalline substrate;

Step 2: on single crystalline substrate, the epitaxial growth monocrystal thin films;

Step 3: deposition one deck SiO on the surface of monocrystal thin films ₂nano thin-film;

Step 4: utilize the method for dual intensity state nitrogen Implantation, from SiO ₂the nitrogen element is injected on the surface of nano thin-film downwards, at SiO ₂the following formation p-type doped layer of nano thin-film, form sample;

Step 5: sample is done to quick thermal annealing process;

Step 6: the SiO that removes sample surfaces ₂nano thin-film, complete preparation.

2. the doping method of p-type zinc telluridse monocrystal thin films material according to claim 1, wherein the material of single crystalline substrate is ZnTe, GaSb, GaAs or Si.

3. the doping method of p-type zinc telluridse monocrystal thin films material according to claim 1, wherein this monocrystal thin films is the non-doping of having a mind to, its thickness is greater than 100nm.

4. the doping method of p-type zinc telluridse monocrystal thin films material according to claim 3, wherein the epitaxial growth monocrystal thin films is to adopt molecular beam epitaxy or metal-organic chemical vapor deposition equipment.

5. the doping method of p-type zinc telluridse monocrystal thin films material according to claim 1, wherein SiO ₂the thickness of nano thin-film is 50-100nm, and depositing temperature is room temperature or lower than 200 ℃; Deposition SiO ₂the method of nano thin-film is magnetron sputtering, chemical vapour deposition (CVD) or pulsed laser deposition.

6. the doping method of p-type zinc telluridse monocrystal thin films material according to claim 1, be 20-30keV, 1.0 * 10 when wherein the energy of nitrogen Implantation and dosage are lower state respectively ¹⁴-5.0 * 10 ¹⁴cm ^-2; During upper state, be 60-80keV, 1.0 * 10 ¹⁵-5.0 * 10 ¹⁵cm ^-2.

7. the doping method of p-type zinc telluridse monocrystal thin films material according to claim 1, wherein quick thermal annealing process is to anneal in the blanket of nitrogen of normal pressure 5-10sccm flow, and annealing temperature is 350-500 ℃, and annealing time is 1-5min.

8. the doping method of p-type zinc telluridse monocrystal thin films material according to claim 1, wherein the hole concentration scope of p-type doped layer is 1 * 10 ¹⁸-1 * 10 ²⁰cm ^-3.

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