TWI458106B - Structure and fabrication of copper indium gallium - selenide film with high carrier mobility - Google Patents

Description

High carrier mobility copper indium gallium selenide film structure and manufacturing method thereof

The invention relates to a structure and a manufacturing method of a high carrier mobility copper indium gallium selenide film, in particular to a manufacturing method for improving the quality of a main absorption layer film of a copper indium gallium selenide solar cell and its carrier mobility.

Copper indium gallium selenide thin film solar cells have gradually emerged in the current solar industry. Copper indium gallium selenide thin films are semiconductors with direct energy gaps, and the composition of copper indium gallium selenide semiconductor materials can be controlled to control the wavelength band of absorption wavelength. In addition, the copper indium gallium selenide film has a very high absorption coefficient, and these advantages make the copper indium gallium selenide film a potential material for development in the solar industry.

The copper indium gallium selenide film plays the role of a light absorbing layer in the element, and exhibits P-type conductivity. The conductivity of the P-type does not need to be formed by doping the external element, but by its own inherent defects. Lead to formation. The essential defects include three kinds of gaps, three kinds of gaps and six kinds of misalignments. The related research results show that the difference in the dominance performance of the polycrystalline copper indium gallium selenide film also affects the film quality. Therefore, improving the quality and characteristics of the copper indium gallium selenide film and improving the device performance has become an important research goal.

In the past, in the evolution of semiconductors, many research experiments have found that on the blue light-emitting diode components, a good quality gallium nitride film is to be epitaxially deposited, and a low-temperature nitride is often added to the interface as a buffer layer. For example, an aluminum nitride film. Hiromtsua et al. first explained the function of the aluminum nitride buffer layer. The step of growing the gallium nitride of the aluminum nitride buffer layer is as follows: (1) the aluminum nitride is first deposited into a buffer layer having the same column height; (2) growing a gallium nitride core at a high temperature; (3) continuing to grow the core; (4) forming an island shape; (5) lateral growth; and (6) polymerizing and continuing to grow to obtain a smooth surface film.

It can be seen from the above steps that the buffer layer has the characteristics of improving stress and improving the quality of the film, and Amano et al. succeeded in growing transparent gallium nitride without surface cracks by using MOCVD epitaxial low-temperature aluminum nitride buffer layer. Akasaki et al. used X-ray diffraction spectroscopy and photoexcitation spectroscopy to verify that the epitaxial gallium nitride film has a perfect lattice arrangement after the addition of a low-temperature aluminum nitride buffer layer. The concentration of the donor is thus reduced to 1 × 10 ¹⁵ cm ^-3 , and the electron mobility is increased by more than one order.

In view of the above disadvantages of the prior art, the main purpose of the present invention is to improve the carrier mobility and epitaxial quality of the main insulative layer of copper indium gallium selenide, and to add an aluminum nitride film between the substrate and the copper indium gallium selenide film to optimize the process. Parameters to improve the quality of the main absorber film and carrier mobility.

In order to achieve the above object, a high-carrier mobility copper indium gallium selenide film structure and a manufacturing method are provided according to the present invention, including a substrate, an electrode layer formed on the substrate, and a buffer layer formed on the electrode layer. And the buffer layer is an aluminum nitride film of different process conditions; and an absorption layer is formed on the buffer layer, wherein the absorption layer is a copper indium gallium selenide semiconductor material, and the aluminum nitride buffer layer is adjusted to Optimize the conditions to improve the quality and carrier mobility of the main absorption layer of copper indium gallium selenide.

The above summary, the following detailed description and the accompanying drawings are intended to further illustrate the manner, the Other objects and advantages of the present invention will be described in the following description and drawings.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can readily appreciate other advantages and functions of the present invention from the disclosure herein.

Please refer to FIG. 1 , which is a schematic diagram of an optimized structure of a copper indium gallium selenide film according to the present invention. As shown in the figure, the structure includes a substrate 1 , an electrode layer 2 formed on the substrate, and the electrode layer 2 is metal. An electrode formed of two or more metal compositions or metal patterns, and then a buffer layer 3 is formed on the electrode layer 2, and the buffer layer 3 is an aluminum nitride film of different process conditions; and an absorbing layer 4 is formed in the buffer Above the layer 3, wherein the absorbing layer 4 is copper indium gallium selenide, copper indium selenide, copper indium gallium sulphide, copper indium sulphide, and other at least one of five elements of copper, indium, gallium, selenium and sulfur. The composition of the compound enhances the film quality and carrier mobility of the copper indium gallium selenide main absorption layer 4 through the buffer layer 3.

The substrate 1 used in the present invention is a high temperature resistant Corning glass 1737 (softening point 975 ° C), and all substrates are subjected to an ultrasonic vibration process of an acetone solution, a methanol solution, and a deionized aqueous solution to remove impurities such as oil stains and debris on the surface of the glass. After performing the organic cleaning step, the oxide buffer etchant (NH ₄ F: HF = 6:1) was used for 10 seconds, and the flushing was taken out for three minutes, and then dried by nitrogen. This method can etch the natural oxide layer and reduce it. The possibility of peeling the surface of the deposited film. The invention modulates various conditions of the sputter deposition of the aluminum nitride film, so as to have good electrical properties and quality in the subsequently deposited copper indium gallium selenide main absorption layer 4.

Before the sputtering, we pumped the chamber pressure to 3.0 × 10 ^-4 torr or less and then introduced the mixed gas Ar (95%) / H ₂ (5%). In the sputtering process, a quartz lamp tube is used to heat the substrate 1, and before depositing the film, the substrate 1 is heated to 500 ° C for one hour to clean the substrate 1 , and after the substrate 1 is cooled to room temperature, the deposition buffer layer is started. 3 film, when the temperature drops to room temperature, the chamber pressure is raised to 1 × 10 ^-1 torr, a thin molybdenum electrode layer 2 is sputtered, and when the aluminum nitride film is deposited successively, the substrate is blocked by a shutter. After about 1 hour, it was deposited on the substrate 1 to make the film more uniform. When the buffer layer 3 is completed, the chamber pressure is immediately reduced to 5 × 10 ^-3 torr, a copper indium gallium film is deposited, and after the reaction is completed, a nitrogen gas vacancy can be introduced, as shown in Fig. 2. It shows that when the copper indium gallium film is grown and selenized, it adopts two-stage temperature rise (low temperature, high temperature) process control: in the first stage, we use 350 ° C to grow for 1 minute to diffuse selenium to the sputtered copper indium gallium. film. The second stage of high temperature diffusion at 500 ° C for 5 minutes, the effect is the same as the use of gaseous selenium and hydrogen selenide caused by the crystallization of brass.

After the completion of the reaction, if a vacuum is applied to the vacuum immediately, the film may be broken or peeled off due to the stress generated by the temperature difference. Or, the quartz lamp tube encounters a low temperature gas at a high temperature state, and is broken due to thermal expansion and contraction. Therefore, after each step of the above steps, a small amount of process argon gas is continuously introduced, so that the temperature slowly drops below Vacuuming at around 100 °C to ensure that the system and test samples are not damaged.

In order to verify the electrical influence of different buffer layers on the film during low temperature growth, copper-indium gallium selenide film without buffer layer was prepared with copper gallium target (CuGa) and indium target (In) as standard test piece, which was taken by scanning electron microscope. Copper indium gallium selenide thin film with different plating rates As shown in Fig. 3, it can be observed that the thickness of the copper indium gallium selenide film of different plating rates is about 2-3 um, and the film of CuGa:In=6:5 has larger crystal grains.

Figure 4 is an XRD analysis of CIGS films with different plating rates. It can be seen from the figure that the peaks of CuGa:In=6:4, 6:5, and 6:6 are all in the phase of copper indium gallium selenide, which is CuGa:In The CIGS film of =6:5 has a smaller full width at half maximum. The mobility and concentration relationship of the copper indium gallium selenide film at different plating rates of CuGa and In targets are shown in Fig. 5. The best electrical conductivity ratio is CuGa:In=6:5 CIGS film, the carrier mobility is 9.33cm ² /V. Sec, carrier concentration 8.50 × 10 ¹⁵ cm ^-3 .

According to the analysis of copper indium gallium selenide film with different plating rates, the CuGa:In=6:5 copper indium gallium selenide film has better film quality and electrical properties. Therefore, CuGa:In=6:5 copper indium is used successively. The gallium selenide film was used as a standard test piece for subsequent experiments.

Adding an aluminum nitride buffer layer 3, the copper indium gallium selenide film prepared by different sputtering time, the side image taken by a scanning electron microscope and the ratio of Al atom distribution are shown in Fig. 6, which shows that Al The atomic ratio of atoms above and below the film. The copper indium gallium selenide film containing the aluminum nitride buffer layer 3 sputtered for 10 minutes has a relatively uniform A1 atomic distribution. Figure 7 is an X-ray diffractometer analysis diagram of a copper indium gallium selenide film with a different thickness of aluminum nitride buffer layer 3. The aluminum nitride buffer layer 3 can be sputtered for 5, 10, and 15 minutes. The peak of the copper indium gallium selenide film is in the phase of copper indium gallium selenide, and has a smaller half width than the copper indium gallium selenide film without the aluminum nitride buffer layer.

The mobility and concentration relationship of a copper indium gallium selenide film carrier having a different thickness of aluminum nitride buffer layer 3 is shown in Fig. 8. The aluminum nitride buffer layer 3 has a sputtering time of 10 minutes, and the copper indium gallium selenide film has the best electrical property, and its carrier mobility is 29.25 cm ² /V. Sec, carrier concentration 5.63 × 10 ¹⁵ cm-3. From the above analysis data, it is known that the copper indium gallium selenide film containing the aluminum nitride buffer layer 3 sputtered for 10 minutes has better electrical properties and film quality than the CIGS film without the buffer layer.

Adding a layer of aluminum nitride buffer layer 3 to the copper indium gallium selenide solar cell component, the short-circuit current and the filling factor of the solar cell characteristics are improved compared with the component without the buffer layer, therefore, adding a buffer layer 3 effectively improves solar energy The characteristics of the battery.

The above-described embodiments are merely illustrative of the features and functions of the present invention, and are not intended to limit the scope of the technical scope of the present invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the scope of the claims described below.

1‧‧‧Substrate

2‧‧‧electrode layer

3‧‧‧buffer layer

4‧‧‧Absorbent layer

RT‧‧‧ room temperature

T1‧‧‧The time when the substrate is cleaned at high temperature

T2‧‧‧Aluminum nitride film growth time

t3‧‧‧Copper Indium Gallium Selenide Film Growth Time

Fig. 1 is a schematic view showing the optimized structure of the copper indium gallium selenide film of the present invention.

Fig. 2 is a schematic view showing the optimized structure of the copper indium gallium selenide film of the present invention and the temperature of the method.

Fig. 3 is a schematic view of a copper indium gallium selenide film before the improvement by a scanning electron microscope.

Fig. 4 is a schematic diagram showing the experimental results obtained by the Hall measurement method for the copper indium gallium selenide film before the improvement.

Figure 5 is a schematic diagram showing the experimental results of the X-ray diffractometer before the improvement of the copper indium gallium selenide film.

Fig. 6 is a schematic view showing the optimized structure and method of the copper indium gallium selenide film of the present invention taken by a scanning electron microscope.

Figure 7 is a schematic diagram showing the experimental results of the X-ray diffractometer for the optimized structure and method of the copper indium gallium selenide film of the present invention.

Fig. 8 is a schematic view showing the experimental results obtained by the Hall measurement method for the optimized structure and method of the copper indium gallium selenide film of the present invention.

1‧‧‧Substrate

2‧‧‧electrode layer

3‧‧‧buffer layer

4‧‧‧Absorbent layer

Claims (16)

A high carrier mobility copper indium gallium selenide thin film structure includes: a substrate; an electrode layer formed on the substrate; and a buffer layer formed on the electrode layer at a low temperature between room temperature and 300 ° C And an absorbing layer formed directly on the buffer layer by two-stage temperature rise, and the absorbing layer is a copper indium gallium selenide semiconductor material, which is added to the buffer layer to produce a high carrier mobility of copper indium gallium selenide The absorption layer and the quality of the main absorption layer of the copper indium gallium selenide are improved, wherein the first stage is low temperature diffusion and the second stage is high temperature selenization. For example, the high carrier mobility copper indium gallium selenide thin film structure according to the first aspect of the patent application, wherein the substrate is a group of glass, metal and polymer materials. For example, the high-carrier mobility copper indium gallium selenide thin film structure according to the first aspect of the patent application, wherein the electrode layer is an electrode formed of a metal, two or more metal compositions or metal patterns. For example, the high carrier mobility copper indium gallium selenide thin film structure of the first application patent range, wherein the buffer layer is an aluminum nitride film, a gallium nitride film, an aluminum oxide film, a zinc oxide film, and a copper oxide film. Group. For example, the high carrier mobility copper indium gallium selenide thin film structure of claim 1 wherein the buffer layer has a thickness ranging from 20 nm to 500 nm. For example, the high carrier mobility copper indium gallium selenide thin film structure of the first application patent range, wherein the absorption layer can further be copper indium gallium selenide, copper indium selenide, copper indium gallium sulfide, copper indium sulfur, and others. a compound composed of at least one of five elements of copper, indium, gallium, selenium and sulfur. For example, the high carrier mobility copper indium gallium selenide thin film structure of the first application patent range, wherein the absorption layer has a process temperature ranging from 300 ° C to 600 ° C. For example, the high carrier mobility copper indium gallium selenide thin film structure of claim 1 wherein the thickness of the absorption layer must be greater than or equal to 500 nanometers. A method for fabricating a high carrier mobility copper indium gallium selenide film, comprising: (a) providing a substrate; (b) forming an electrode layer on the substrate; (c) forming a buffer layer on one side of the electrode layer, wherein The buffer layer process temperature is between room temperature and 300 ° C; and (d) further forming an absorption layer via the two-stage temperature rise on the buffer layer, and the absorption layer is a copper indium gallium selenide semiconductor material, through the buffer layer In order to produce a high-carrier mobility of copper indium gallium selenide main absorption layer, and improve the quality of the copper indium gallium selenide main absorption layer, wherein the first stage is low temperature diffusion, and the second stage is high temperature selenization. For example, the method for manufacturing a high carrier mobility copper indium gallium selenide film according to claim 10, wherein the substrate is a group of glass, metal and polymer materials. The method for fabricating a high carrier mobility copper indium gallium selenide film according to claim 10, wherein the electrode layer is an electrode formed of a metal, two or more metal compositions or a metal pattern. For example, the method for manufacturing a high carrier mobility copper indium gallium selenide film according to claim 10, wherein the buffer layer is an aluminum nitride film, a gallium nitride film, A group of aluminum oxide films, zinc oxide films, and copper oxide films. For example, the method for manufacturing a high carrier mobility copper indium gallium selenide film according to claim 10, wherein the buffer layer has a thickness ranging from 20 nm to 500 nm. For example, the method for manufacturing a high-carrier mobility copper indium gallium selenide film according to claim 10, wherein the absorption layer can further be copper indium selenide, copper indium gallium sulfide, copper indium sulfur, and other copper, indium, and the like. a compound composed of at least one of five elements of gallium, selenium and sulfur. For example, the method for manufacturing a high carrier mobility copper indium gallium selenide film according to claim 10, wherein the absorption layer has a process temperature ranging from 300 ° C to 600 ° C. For example, the method for manufacturing a high carrier mobility copper indium gallium selenide film according to claim 10, wherein the thickness of the absorption layer must be greater than or equal to 500 nm.