Indium phosphide crystal containing zinc and magnesium, single crystal wafer, preparation method for indium phosphide crystal, and device

Abstract

An indium phosphide crystal containing zinc and magnesium, a single crystal wafer, a preparation method for the indium phosphide crystal, and a device. Specifically, provided is an indium phosphide crystal, which is a P-type indium phosphide single crystal, wherein the indium phosphide crystal contains 0.5 ppm to 500 ppm of zinc and 0.5 ppm to 1000 ppm of magnesium. The present invention also relates to a preparation method for the indium phosphide crystal containing zinc and magnesium, and a device prepared by using the indium phosphide crystal. The indium phosphide crystal containing zinc and magnesium has low dislocation density, few defects, and high yield.

Description

Indium phosphide crystals containing zinc and magnesium, single wafers, their preparation methods and devices Technical Field

[0001] This application relates to the field of semiconductor processing and manufacturing, and in particular to indium phosphide crystals and methods for preparing the same; it also relates to indium phosphide single wafers made from the indium phosphide crystals and methods for preparing the same, as well as devices including the indium phosphide crystals. Background Technology

[0002] Indium phosphide (InP), a III-V compound semiconductor material, exhibits higher electron mobility than materials such as silicon or gallium arsenide. It also possesses high photoelectric conversion efficiency, strong radiation resistance, and high thermal conductivity. These excellent properties make it widely used in integrated circuits, high-speed and high-frequency devices, optoelectronic devices, and fiber optic communications, among other fields.

[0003] The fabrication of InP single-crystal wafers typically involves steps such as growing the single crystal, cutting rough wafers from the single crystal rod, edge grinding, polishing, rough polishing, fine polishing, cleaning, and drying. Because InP has a very high dissociation pressure (approximately 2.75 MPa) near its melting point (approximately 1335 ± 7 K), its critical shear stress (CRSS) and stacking fault energy are relatively low. This leads to a high likelihood of twinning and dislocation density during the growth of intrinsic InP single crystals, typically reaching hundreds, thousands, or even tens of thousands. To meet application requirements, certain impurities are intentionally introduced during the growth of InP single crystals to alter their electronic structure and conductivity. By introducing different impurities, P-type or N-type InP single crystals can be formed. However, the growth of both types of InP single crystals (i.e., P-type InP single crystals and N-type InP single crystals) still inevitably faces problems such as low stacking fault energy, twinning defects, low carrier concentration, and low yield.

[0004] Summary of the Invention

[0005] Therefore, the existing technology requires an InP crystal with low dislocation density, no twin defects, good electrical conductivity, and high yield, as well as a method for its preparation.

[0006] This application is proposed to solve the above problems. It obtains indium phosphide single crystals with low dislocation density, few twins and high carrier concentration by simultaneously doping two or more doping elements in the indium phosphide crystal growth melt, thereby improving the yield of indium phosphide single crystals.

[0007] Specifically, the first aspect of this application provides an indium phosphide crystal, which is a P-type indium phosphide single crystal, wherein the indium phosphide crystal contains 0.5 ppm to 500 ppm of zinc (Zn) and 0.5 ppm to 1000 ppm of magnesium (Mg).

[0008] This application also provides a method for preparing indium phosphide crystals, the method comprising the steps of placing phosphorus, polycrystalline indium phosphide, a dopant containing magnesium and a dopant containing zinc (or a dopant containing zinc and magnesium), together with a sealant, into a growth container (e.g., a crucible) containing a seed crystal; and placing the container into a crystal growth furnace and heating it to a temperature above the melting point of indium phosphide; preferably, the zinc content in the obtained indium phosphide crystal is from 0.5 ppm to 500 ppm, and the magnesium content is from 0.5 ppm to 1000 ppm.

[0009] In another aspect, this application provides an indium phosphide single crystal wafer, which is made from an indium phosphide crystal according to the above description or from an indium phosphide crystal obtained by the above method.

[0010] In another aspect, this application provides an electronic device or optoelectronic device that is made of or contains components made of the aforementioned indium phosphide single crystal wafer.

[0011] This application also provides the use of a combination of magnesium-containing dopants and zinc-containing dopants, or dopants containing zinc and magnesium, in the preparation of indium phosphide crystals to increase carrier concentration while reducing dislocation density, reducing twin defects, and / or increasing the yield of indium phosphide crystals.

[0012] The indium phosphide crystal obtained in this application, which is simultaneously doped with zinc and magnesium, is a P-type indium phosphide single crystal. It has a low dislocation density and reduces the formation of twins. Therefore, the yield of indium phosphide crystal is high and a single crystal wafer with uniform and stable performance can be obtained. At the same time, the obtained P-type indium phosphide crystal has good conductivity and can therefore be used in optoelectronic devices such as lasers and photodetectors, electronic devices such as transistors, and high-frequency components. Attached Figure Description

[0013] Figure 1 is a cross-sectional view of an embodiment of a crystal growth apparatus including a sealed container for growing zinc-doped and magnesium-doped indium phosphide single crystals.

[0014] Figure 2 is a schematic diagram of the single crystal rod fixing device used in the fabrication of a single crystal wafer according to the present disclosure. Detailed Implementation

[0015] To make the purpose, technical solution, and beneficial technical effects of this application clearer, the following detailed description is provided in conjunction with specific embodiments. It should be understood that the embodiments described in this specification are merely for explaining this application and are not intended to limit it.

[0016] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0017] Unless otherwise specified, all embodiments and preferred embodiments of this application may be combined to form new technical solutions, and such technical solutions shall be considered to be included in the disclosure of this application.

[0018] Unless otherwise specified, all technical features, optional technical features, or preferred technical features of this application may be combined with each other to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0019] As mentioned above, this application provides an indium phosphide crystal, which is a P-type indium phosphide single crystal, wherein the indium phosphide crystal contains 0.5 ppm to 500 ppm of zinc and 0.5 ppm to 1000 ppm of magnesium.

[0020] In existing technologies, a single element is typically used to form P-type indium phosphide crystals, and there are no reports of magnesium + zinc co-doped indium phosphide crystals. Even when existing technologies occasionally involve indium phosphide crystals containing both magnesium and zinc, one element is dominant, while the other exists as a trace impurity element, with a significant difference in their content ratios (more than a million times).

[0021] Without being bound by any theory, the applicant has discovered:

[0022] (1) In actual crystal growth, zinc has a significant impurity hardening effect in InP. Doping with a certain amount of zinc can effectively strengthen the lattice strength of InP crystals, thereby greatly reducing the point defect density of InP crystals. However, zinc-doped InP is prone to twinning during crystal growth, resulting in a low single crystal yield, which is also a reason for the high cost of InP single crystals. In particular, in recent years, the market has increasingly demanded higher carrier concentrations for P-type InP crystals, which requires the addition of more zinc-containing dopants during InP crystal growth. However, the addition of zinc alone will greatly increase the probability of twinning during InP crystal growth, significantly reducing the single crystal yield.

[0023] (2) In actual production, it was found that the addition of magnesium as a p-type dopant can suppress twin formation to a certain extent. This may be because the introduction of magnesium increases the viscosity of the melt during InP crystal growth, which is beneficial to the stability of the indium phosphide hot melt. However, magnesium has little effect on strengthening the lattice strength, resulting in a relatively high point defect density in magnesium-doped InP crystals, reaching hundreds or even thousands (cm²). -2 Furthermore, due to the small segregation coefficient of magnesium in the InP crystal growth process, it is difficult to achieve the growth of InP crystals with high carrier concentration, especially at the head of the crystal rod (according to the article "Electrical and optical properties of Mg-,Ca-, and Zn-doped InP crystals grown by the synthesis, solid diffusion technique" published by Eishi Kubota et al. (J.Appl.Phys.55(10),15May 1984,3779-3784,American Institute of Physics), the segregation coefficient of magnesium in InP crystals is 3E-2). In order to meet the market demand for high carrier concentration, a large amount of magnesium-containing dopants must be added. Even so, it is difficult to grow crystals that meet market demands at the head of the crystal. Moreover, the high magnesium content basically remains at the tail, which will cause some damage to the formation of single crystals of InP crystals.

[0024] (3) In this application, zinc and magnesium are used as P-type dopants in a certain proportion and are co-doped into indium phosphide crystal. This can reduce the dislocation density of the crystal and suppress the formation of twins to a certain extent. In other words, there is a certain degree of synergistic effect, which can effectively improve the crystallization rate (yield) of single crystal. Furthermore, by adjusting the doping ratio, the application requirements of low dislocation density and high carrier concentration can be fully met.

[0025] In this article, the "segregation coefficient," also known as the effective distribution coefficient, refers to the concentration of impurities at the solid-liquid interface due to the different solubilities of impurities in the different phases. The segregation coefficient is denoted by K, where K = (solubility of impurity in the solid phase) / (solubility of impurity in the liquid phase) (K = Cs / Cl). The segregation coefficients of each element can be determined by methods known in the art, such as those described in the article "Growth and Properties of Magnesium-Doped Low-Dislocation Indium Phosphate Single Crystals" by Fang Dunfu et al. (Journal of Applied Sciences, Vol. 1, No. 3, July 1983).

[0026] In some embodiments of this application, the zinc content in the indium phosphide crystal can be from 0.5 ppm to 500 ppm; for example, the zinc doping amount can be 0.5 ppm, 0.8 ppm, 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, 10 ppm, 20 ppm, 40 ppm, 50 ppm, 80 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, etc., or any content range consisting of any of the above-mentioned contents or any contents disclosed in the embodiments of this application as endpoints. As an example, the zinc content in the indium phosphide crystal can be from 0.8 ppm to 500 ppm, preferably from 1 ppm to 400 ppm, more preferably from 1.2 ppm to 300 ppm. In some preferred embodiments of this application, the zinc content in the indium phosphide crystal can be from 5 ppm to 450 ppm, preferably from 10 ppm to 400 ppm, more preferably from 20 ppm to 300 ppm, and even more preferably from 25 ppm to 200 ppm.

[0027] In some embodiments of this application, the magnesium content in the indium phosphide crystal can be from 0.5 ppm to 1000 ppm; for example, the magnesium doping amount can be 0.5 ppm, 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, 20 ppm, 40 ppm, 50 ppm, 80 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 800 ppm, 1000 ppm, etc., or any content range consisting of any of the above-mentioned contents or any contents disclosed in the embodiments of this application as endpoints. As an example, the magnesium content in the indium phosphide crystal can be from 0.8 ppm to 800 ppm, preferably from 1 ppm to 500 ppm, and more preferably from 2 ppm to 300 ppm. In some preferred embodiments of this application, the magnesium content in indium phosphide crystals can be from 1 ppm to 800 ppm, preferably from 1.5 ppm to 500 ppm, more preferably from 1.8 ppm to 350 ppm, and even more preferably from 2 ppm to 250 ppm.

[0028] In some embodiments of this application, in addition to magnesium and zinc, indium phosphide crystals may contain other elements added or doped for other purposes. In some preferred embodiments of this disclosure, the other elements may be selected from elements with low segregation coefficients that do not affect the main properties of the original P-type indium phosphide crystal or its use in single-wafer epitaxy.

[0029] It should be noted that the indium phosphide crystals provided in this application are typically in the form of single crystal rods. For indium phosphide crystals in the form of single crystal rods, it has been found that the content of doping elements (which is directly proportional to the carrier concentration CC) varies at different cross-sections along the growth direction of the single crystal rod, mainly due to the segregation coefficient K of the doping element (impurity element) in indium phosphide.

[0030] The following formula gives the distribution relationship of the dopant element content in the crystal rod (according to Pfann, WG, "Zone Melting").

[0031] C x =K·C0(1-X) (K-1)

[0032] Where C x denoted as , where is the solubility of the dopant element in the solid phase at different cross sections; X is the ratio of the length of the crystallized portion to the total length of the crystal; C0 is the solubility of the dopant element in the liquid phase in the molten state before crystallization.

[0033] That is, the distribution of zinc and magnesium dopants (K<1) in indium phosphide crystals is not uniform; their content gradually increases non-linearly from the head of the crystal rod to the tail of the crystal. Therefore, in the case of indium phosphide crystals in the form of single crystal rods or in other cases where the distribution of dopants in indium phosphide crystals is not uniform, the range of dopant content in indium phosphide crystals specified in this application should be understood as the dopant content at any position of the finished single crystal rod (excluding the very beginning and the very end of the single crystal rod that should be discarded during processing) falling within the specified range.

[0034] The indium phosphide crystal provided in this application can also be in the form of a single wafer. The single wafer can be obtained, for example, by cutting an indium phosphide single crystal rod. When the indium phosphide crystal is in the form of a single wafer, the types of doping elements and the content of the doping elements in the crystal are also as described above.

[0035] The indium phosphide crystal in this application is a p-type indium phosphide single crystal. In some preferred embodiments of this application, the carrier concentration of the indium phosphide single crystal is 1×10⁻⁶. 17 cm -3 Up to 5×10 19 cm -3 For example, 1×10 18 cm -3 Up to 1×10 19 cm -3 1×10 is preferred 18 cm -3 Up to 8×10 18 cm -3 Or 8×10 17 cm-3 Up to 9×10 18 cm -3 9×10 is preferred 17 cm -3 Up to 7×10 18 cm -3 .

[0036] In this article, carrier concentration refers to the concentration per unit volume (cm³). 3 The carrier concentration is the number of charge carriers. Under conditions of room temperature and no compensation, it is equal to the concentration of ionized impurities. The carrier concentration can be determined using methods known in the art, such as a Hall effect meter.

[0037] The indium phosphide single crystal of this application exhibits low dislocation density and uniform dislocation distribution. In some preferred embodiments of this application, the average dislocation density of the indium phosphide crystal can be 800 / cm². 2 Below, or 500 / cm 2 The following may be 100 / cm 2 Below, even 80 / cm 2 The following is a particularly preferred embodiment: the average dislocation density of indium phosphide crystal can reach 50 / cm². 2 Or lower.

[0038] In this application, the dislocation density of zinc and magnesium-doped indium phosphide single crystals was determined using the method described in GB / T20230-2022 "Indium Phosphide Single Crystals".

[0039] This application also provides a method for preparing indium phosphide crystals, the method comprising the steps of placing phosphorus, polycrystalline indium phosphide, a dopant containing magnesium and a dopant containing zinc, or a dopant containing magnesium and zinc, together with a sealant, into a growth container (e.g., a crucible) containing a seed crystal; and the steps of placing the container into a crystal growth furnace and heating it to a temperature above the melting point of indium phosphide.

[0040] Preferably, the zinc content in the indium phosphide crystal is from 0.5 ppm to 500 ppm, for example, 0.5 ppm, 0.8 ppm, 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, 10 ppm, 20 ppm, 40 ppm, 50 ppm, 80 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, etc.; and preferably, the magnesium content in the indium phosphide crystal is from 0.5 ppm to 1000 ppm, for example, 0.5 ppm, 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, 20 ppm, 40 ppm, 50 ppm, 80 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 800 ppm, 1000 ppm, etc., or any content range formed by taking any of the above relative amounts or any of the relative amounts disclosed in the embodiments of this application as endpoints.

[0041] In this application, the magnesium and zinc content in indium phosphide crystals was measured using glow discharge mass spectrometry (GDMS). In a glow discharge ion source, a potential difference is applied between the cathode (the sample being analyzed) and the anode, and the plasma is maintained by introducing an inert gas (typically argon). Inert gas ions and fast neutral particles formed in the plasma are attracted to the sample surface, and their impact causes surface sputtering, generating neutral particles. These neutral particles diffuse into the plasma, are subsequently ionized in the plasma's equipotential region, and can then be extracted into the mass spectrometer for quantitative analysis. Refer to the current testing standard – DB35 / T 1146-2011 Determination of Impurity Element Content in Silicon Materials by Glow Discharge Mass Spectrometry.

[0042] In this application, the dopant containing the dopant element used as a raw material in the method for preparing indium phosphide crystals is selected from the element itself, a phosphide of the element, an alloy of the element and indium, or a mixture of the above substances. Hereinafter, the term "dopant" refers to a substance used to provide elements such as magnesium or zinc in the preparation of indium phosphide crystals; elemental magnesium or zinc can be used, or magnesium-containing compounds and / or zinc-containing compounds suitable for industrial production environments can be used. The dopant used is preferably of high purity, preferably 99.00% or higher, for example 99.99% or higher.

[0043] For example, in some preferred embodiments of this application, the dopant containing magnesium is selected from magnesium, magnesium phosphides (e.g., Mg3P2), magnesium-indium alloys, or any mixture thereof. For example, in some preferred embodiments of this application, the dopant containing zinc is selected from zinc, zinc phosphides, zinc-indium alloys, or mixtures thereof. Alternatively, zinc and magnesium may be present in the same dopant, in which case the dopant is both a magnesium-containing dopant and a zinc-containing dopant.

[0044] In this application, the equipment (e.g., growth container, furnace, etc.) used in the indium phosphide crystal preparation method can be conventional equipment known or commonly used in the art for preparing N-type indium phosphide single crystals or P-type indium phosphide single crystals.

[0045] In this application, the raw materials phosphorus, polycrystalline indium phosphide, dopants, and sealants used in the indium phosphide crystal preparation method can all be conventional raw materials known in the art for preparing N-type or P-type indium phosphide single crystals, or they can be prepared in-house or obtained commercially. These raw materials are typically of high purity, preferably 99.00% or higher, for example, 99.99% or higher.

[0046] In this application, the operation of loading phosphorus, indium phosphide polycrystalline material, magnesium-containing dopant, zinc-containing dopant, or a dopant containing both zinc and magnesium, and a sealant into a growth container can be implemented in various ways. For example, phosphorus, indium phosphide polycrystalline material, magnesium-containing dopant, zinc-containing dopant, or a dopant containing both zinc and magnesium, and a sealant can be added to the growth container simultaneously or sequentially. Alternatively, magnesium-containing dopant and / or zinc-containing dopant, or a dopant containing both zinc and magnesium, can be pre-mixed into the indium phosphide polycrystalline material (or the dopant can be introduced during the preparation of the indium phosphide polycrystalline material to form an indium phosphide polycrystalline material containing the dopant element) before being added to the growth container, and so on. All of these implementation methods can be used to prepare the indium phosphide crystal of this application. Based on this, those skilled in the art can also conceive of other equivalent implementation methods, and all the above-mentioned implementation methods and other equivalent implementation methods are considered to be within the scope of disclosure of this application.

[0047] In some preferred embodiments of this application, the amount of the magnesium-containing dopant, zinc-containing dopant, or dopant containing both zinc and magnesium is such that the zinc content in the indium phosphide crystal is from 0.5 ppm to 500 ppm, and the magnesium content in the indium phosphide crystal is from 0.5 ppm to 1000 ppm. More preferably, the resulting indium phosphide single crystal rod has a carrier concentration of 1 × 10⁻⁶ over its effective length. 17 cm -3 Up to 5×10 19 cm -3 1×10 is preferred 18 cm -3 Up to 1×10 19 cm -3.

[0048] In some embodiments, the method for preparing indium phosphide crystals further includes:

[0049] The step of gradually cooling the melt in the container to obtain P-type indium phosphide single crystals.

[0050] In some preferred embodiments, the step of placing the container in a crystal growth furnace and heating it to a temperature above the melting point of indium phosphide includes: placing the container in the crystal growth furnace and heating it using a multi-temperature zone system, preferably establishing a temperature gradient of 0.1 to 10.0 °C / cm in the single crystal rod growth zone to raise the temperature and maintain it above the melting point of indium phosphide; and then gradually cooling the melt in the container to obtain a P-type indium phosphide single crystal.

[0051] The amounts of phosphorus, polycrystalline indium phosphide, dopant, and sealant used in the indium phosphide crystal preparation method of this application can be determined by those skilled in the art according to actual needs.

[0052] In some preferred embodiments of this application, the method for preparing the crystal is selected from the vertical Bridgman process (VB), vertical gradient condensation (VGF), vapor pressure controlled Czochralski (VCZ), or vertical crucible growth.

[0053] In some preferred embodiments of this application, the method for preparing the crystal is selected from the vertical gradient condensation (VGF) method, in which the crucible can move in the temperature field or the temperature field can change while the crucible remains stationary.

[0054] In some preferred embodiments of this application, the vertical gradient condensation (VGF) method is employed, the steps of which include:

[0055] 1) Phosphorus, indium phosphide polycrystalline, dopants containing magnesium, and dopants containing zinc or containing both zinc and magnesium, along with the sealant boron oxide, are placed into a crucible containing seed crystals.

[0056] 2) Place the crucible described in step 1) inside the growth tube (preferably a quartz tube, but other types of growth tubes may also be used) and seal the growth tube under vacuum;

[0057] 3) Place the growth tube sealed with the crucible from step 2) into the crystal growth furnace (preferably using a multi-temperature zone system for heating, more preferably establishing a temperature gradient of 0.1 to 10.0 °C / cm in the single crystal rod growth zone) to raise the temperature and maintain it above the melting point of indium phosphide.

[0058] 4) Gradually cool the melt in the crucible obtained in step 3) to obtain a P-type indium phosphide single crystal containing zinc and magnesium.

[0059] The container for growing indium phosphide single crystal rods can be fabricated using suitable crucible materials, such as pyrolytic boron nitride (PBN) crucibles. The container or crucible for single crystal growth comprises a cylindrical body, the diameter of which is slightly larger than the diameter of the zinc- and magnesium-doped indium phosphide single crystal rod to be prepared. At the bottom is a small-diameter seed crystal (also called a seed) slot, and a conical transition zone exists between the bottom seed crystal slot and the cylindrical body. The seed crystal slot is used to hold the cylindrical seed crystals used for indium phosphide single crystal preparation.

[0060] The crystal orientation of the upper surface of the seed crystal is the desired surface crystal orientation of the zinc and magnesium doped indium phosphide single crystal substrate, such as (100) or the surface crystal orientation deflected at a certain angle relative to the (100) crystal orientation to the adjacent crystal orientation axis.

[0061] As shown in Figure 1, a suitable sealant 5 (such as boron oxide) and raw material 6 are placed together in crucible 4. The raw material includes phosphorus, polycrystalline indium phosphide, and magnesium-containing and zinc-containing dopants, or dopants containing both zinc and magnesium. The sealant can inhibit the decomposition of indium phosphide material at high temperatures, and also serves to isolate the inner wall of the crucible from the surface of the solid single crystal rod during the melt or single crystal growth process, reducing adhesion between the surface of the grown single crystal rod and the inner wall of the crucible, making it easier to obtain a complete indium phosphide single crystal rod doped with zinc and magnesium. The amount of sealant used is the conventional amount used in this field.

[0062] According to the preparation method described above in this application, indium phosphide crystals as described in the first aspect of this application can be obtained, wherein the indium phosphide crystals are magnesium / zinc dual-doped P-type indium phosphide single crystals.

[0063] Another aspect of this application provides the use of a combination of magnesium-containing dopants and zinc-containing dopants, or dopants containing both zinc and magnesium, in the preparation of indium phosphide crystals to increase carrier concentration while reducing dislocation density, reducing twin defects, and / or increasing the yield of indium phosphide crystals. In a preferred embodiment, the zinc content in the obtained indium phosphide crystal is from 0.5 ppm to 500 ppm, and the magnesium content is from 0.5 ppm to 1000 ppm.

[0064] This application also provides an indium phosphide single-crystal wafer, which is made from the P-type indium phosphide single crystal described above or from the P-type indium phosphide single crystal obtained according to the above method. The indium phosphide single-crystal wafer can be made using conventional methods in the art using the P-type indium phosphide single crystal described above or from the P-type indium phosphide single crystal obtained according to the above method. Zinc- and magnesium-doped indium phosphide single-crystal rods of this application can be cut to produce zinc- and magnesium-doped indium phosphide single-crystal wafers. Industrial preparation methods typically include steps such as cutting rough wafers from single-crystal rods, edge grinding of the rough wafers, polishing, coarse polishing, fine polishing, cleaning, and drying.

[0065] In this application, the diameter of a single wafer should be understood as follows: when the single wafer is circular, it refers to the diameter of the circle; when the single wafer is of other shapes (such as irregular circles, squares, rectangles, etc.), it refers to the diameter of the circle formed by drawing a circle with the center of the single wafer as the center, so that the circle includes all parts of the single wafer.

[0066] In this application, the term "effective length" means the actual length of a single crystal rod that can be cut into a single wafer.

[0067] The thickness of the zinc and magnesium doped indium phosphide single wafers in this application is 200 to 2000 μm, preferably 300 to 1200 μm.

[0068] The zinc- and magnesium-doped indium phosphide single crystal wafer of this application is cut from zinc- and magnesium-doped indium phosphide single crystal rods. The zinc- and magnesium-doped indium phosphide single crystal rods are single crystal rods with a circular cross-section (referred to as circular single crystal rods), and the diameter of the circular cross-section is usually no more than 12 inches, preferably 1 to 8 inches. Of course, the zinc- and magnesium-doped indium phosphide single crystal rods can also be single crystal rods with other cross-sections, such as zinc- and magnesium-doped indium phosphide single crystal rods with a square (square or rectangular) cross-section obtained by processing circular single crystal rods. In this case, the cut wafer is a non-circular zinc- and magnesium-doped indium phosphide single crystal wafer.

[0069] The zinc- and magnesium-doped indium phosphide single crystal wafers of this application are preferably cut from single crystal rods prepared by the method described herein for preparing zinc- and magnesium-doped indium phosphide single crystal rods. The processing of the zinc- and magnesium-doped indium phosphide single crystal wafers of this application is exactly the same as the processing of conventional magnesium-doped single crystals. Specific examples of the processing method of the zinc- and magnesium-doped indium phosphide single crystal wafers of this application can be found in Chinese Patent CN 116043318A, the content of which is incorporated herein by reference.

[0070] The indium phosphide single wafer described in this application can be used for epitaxial growth or further processing to form devices, including but not limited to optoelectronic devices such as lasers, detectors, light-emitting diodes, etc., or electronic devices such as HBTs, MESFETs, PHEMTs, etc.

[0071] This application also provides an electronic or optoelectronic device made of or containing components made of the aforementioned indium phosphide single-crystal wafer. The optoelectronic device includes, for example, a laser, a detector, a light-emitting diode, etc., while the electronic device includes, for example, an HBT, a MESFET, a PHEMT, etc.

[0072] This application can be illustrated through the following implementation scheme:

[0073] 1. An indium phosphide crystal, which is a P-type indium phosphide single crystal, wherein the indium phosphide crystal contains 0.5 ppm to 500 ppm of zinc and 0.5 ppm to 1000 ppm of magnesium.

[0074] 2. The indium phosphide crystal according to embodiment 1, wherein the zinc content is 0.8 ppm to 500 ppm, preferably 1 ppm to 400 ppm, more preferably 1.2 ppm to 300 ppm.

[0075] 3. The indium phosphide crystal according to embodiment 1 or 2, wherein the magnesium content is 0.8 ppm to 800 ppm, preferably 1 ppm to 500 ppm, more preferably 2 ppm to 300 ppm.

[0076] 4. The indium phosphide crystal according to any one of embodiments 1 to 3, wherein the carrier concentration of the indium phosphide crystal is 1 × 10⁻⁶. 17 cm -3 Up to 5×10 19 cm -3 For example, 1×10 18 cm -3 Up to 1×10 19 cm -3 1×10 is preferred 18 cm -3 Up to 8×10 18 cm -3 Or, for example, 8×10 17 cm -3 Up to 9×10 18 cm - 3 8×10 is preferred 17 cm -3 Up to 7×10 18 cm -3 .

[0077] 5. The indium phosphide crystal according to any one of embodiments 1 to 4, wherein the indium phosphide crystal is in the form of an indium phosphide single crystal rod.

[0078] 6. A method for preparing indium phosphide crystals, wherein the indium phosphide crystals are p-type indium phosphide single crystals, the method comprising the step of placing phosphorus, polycrystalline indium phosphide, a dopant containing magnesium, and a dopant containing zinc or a dopant containing both zinc and magnesium, together with a sealant, into a growth container, such as a crucible, containing a seed crystal; and

[0079] The step of placing the container in a crystal growth furnace and heating it to a temperature above the melting point of indium phosphide.

[0080] 7. The method according to embodiment 6 further includes the step of gradually cooling the melt in the container to obtain the P-type indium phosphide single crystal.

[0081] 8. The method according to embodiment 6 or 7, wherein the step of placing the container in the crystal growth furnace and heating it to a temperature above the melting point of indium phosphide includes: placing the container in the crystal growth furnace and heating it using a multi-temperature zone system, preferably establishing a temperature gradient of 0.1 to 10.0 °C / cm in the single crystal growth zone to raise the temperature and maintain it above the melting point of indium phosphide.

[0082] 9. The method according to any one of embodiments 6 to 8, wherein the content of zinc in the obtained indium phosphide crystals is from 0.5 ppm to 500 ppm, and the content of magnesium in the obtained indium phosphide crystals is from 0.5 ppm to 1000 ppm.

[0083] 10. The method according to any one of embodiments 6 to 9, wherein

[0084] The magnesium-containing dopant is selected from magnesium, magnesium phosphides, magnesium-indium alloys, or any mixture thereof;

[0085] The zinc-containing dopant is selected from zinc, zinc phosphides, zinc-indium alloys, or mixtures thereof.

[0086] 11. The method according to any one of embodiments 6 to 10, wherein the method is selected from the vertical Bridgman process (VB), vertical gradient condensation (VGF), vapor pressure controlled Czochralski (VCZ), or vertical crucible growth.

[0087] 12. The use of a combination of magnesium-containing dopants and zinc-containing dopants, or dopants containing zinc and magnesium, in the preparation of indium phosphide crystals to increase carrier concentration while reducing dislocation density, reducing twin defects, and / or increasing the yield of indium phosphide crystals.

[0088] 13. An indium phosphide single crystal wafer, made from an indium phosphide crystal according to any one of embodiments 1 to 5, or an indium phosphide single crystal obtained by the method according to any one of embodiments 6 to 11.

[0089] 14. The indium phosphide single wafer according to embodiment 13, wherein the single wafer is used for epitaxial growth thereon or for further fabrication of devices, the devices including optoelectronic devices, such as lasers, detectors, light-emitting diodes, etc., or electronic devices, such as HBTs, MESFETs, PHEMTs, etc.

[0090] 15. An electronic or optoelectronic device made of or containing components made of an indium phosphide single wafer according to any one of embodiments 13 to 14.

[0091] 16. The optoelectronic device according to embodiment 15 is a laser, a detector, or a light-emitting diode, etc.

[0092] 17. The electronic device according to embodiment 15 is an HBT, MESFET, or PHEMT, etc.

[0093] The indium phosphide crystals containing zinc and magnesium obtained in this application have fewer twins, lower defect density, and higher yield, which can greatly reduce costs and have better electrical properties, thus enabling them to be more widely used in optoelectronic devices such as lasers and photodetectors, as well as high-frequency electronic devices.

[0094] Example

[0095] To better understand this application, the following description will be made in conjunction with embodiments and accompanying drawings. However, it should be understood that these embodiments are merely illustrative examples and are not intended to limit the scope of this application.

[0096] Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing. The instruments used in each example are commercially available.

[0097] Production equipment

[0098] Figure 1 shows a cross-sectional view of an example crystal growth apparatus comprising a sealed container for growing indium phosphide single crystals doped with zinc and magnesium. The apparatus is housed within a high-pressure chamber 1 and may include a growth tube 3 located within a furnace. A heater 2 comprises multiple temperature zones, each individually controlled by a computer controlled by a control system. The pressure within the high-pressure chamber 1 is adjusted to, for example, about 2 to 4 MPa. The temperature of each temperature zone is adjusted to provide the temperature distribution and gradient required for controlling melt solidification, adjusting the temperature distribution and gradient within the furnace to allow the crystallization interface to move upwards through the melt as desired, for example, establishing a temperature gradient of 0.1 to 10 °C / cm in the single crystal growth region and a lower temperature gradient at the seed crystal end. A crucible 4 within the growth tube (quartz tube) 3 has a seed tank for holding a seed crystal 7, from which a single crystal grows. In one embodiment, the crucible 4 may be a pyrolytic boron nitride structure having a cylindrical crystal growth section, a smaller diameter seed tank cylinder, and a tapered transition section. The crystal growth section is open at the top of crucible 4, and its diameter is equal to the diameter of the desired crystal product. In an exemplary embodiment, the seed tank cylinder at the bottom of crucible 4 may have a closed bottom and a diameter slightly larger than that of the seed crystal 7. The cylindrical crystal growth section and the seed tank cylinder may have straight walls or taper outwards at approximately 1 to 30 degrees to facilitate the removal of the crystal from crucible 4.

[0099] The crucible 4 fits inside the growth tube 3 and has a narrow gap between them. The bottom of the growth tube 3 is closed in its seed tank area and sealed at the top after the crucible and raw materials are loaded.

[0100] Because the growth tube-crucible assembly has a funnel shape, a growth tube support is needed to accommodate this funnel shape and keep the growth tube 3 stable and upright inside the furnace. In other embodiments, the growth tube-crucible assembly can maintain different shapes, and the basic structure of the growth tube support will change according to the different shapes.

[0101] In the VGF crystal growth method, the crystallization temperature gradient of a fixed heat source is moved by electrical control, while the crystal remains fixed.

[0102] To implement vertical gradient condensation growth, a required temperature gradient distribution needs to be established within the furnace. The power of the furnace's heating zone is individually controlled by a computer programmed to heat and cool to suit the furnace's crystallization temperature and temperature gradient requirements. For the production of single crystal rods, for example, the furnace temperature fluctuation may need to be controlled within ±1°C. During furnace preparation, polycrystalline phosphorus and indium phosphide raw material 6, including dopants, is loaded into the growth tube 3.

[0103] In this embodiment, elemental magnesium and zinc are used as dopants. A (100) oriented seed crystal is placed in the seed cell of the crucible, followed by the loading of raw material. The raw material (containing an appropriate amount of dopant) is loaded into the crucible, and the crucible is placed in the growth tube 3. The growth tube containing the crucible is connected to a vacuum system for evacuation, and then the growth tube is sealed. The sealed growth tube is then loaded into the furnace, as shown in Figure 1. The furnace is turned on, heating the growth tube and its contents to a temperature above the melting point of indium phosphide, 1050°C. The temperature gradient at the crystallization interface can be adjusted from 0.1 to 10°C / cm depending on the position of the single crystal rod. The entire temperature distribution is adjusted to achieve a crystallization rate of 2 to 5 mm / h.

[0104] The zinc- and magnesium-doped indium phosphide single crystal rods grown using the above exemplary growth process parameters can be used to cut wafers.

[0105] The designed growth program can achieve a suitable growth rate and a suitable temperature gradient near the solid-liquid interface from the seed crystal to the end of single crystal growth (or the complete solidification of the melt into a solid single crystal).

[0106] Under this growth procedure and with the appropriate amount of dopant, single crystal growth is maintained throughout the entire length of the single crystal rod. For example, indium phosphide single crystal rods doped with zinc and magnesium with diameters ranging from 2 to 6 inches can be grown.

[0107] After all the raw materials in the crucible have solidified, the grown single crystal rod is cooled to room temperature under controlled temperature conditions.

[0108] Performance testing

[0109] The appearance quality of the prepared zinc and magnesium doped indium phosphide single crystal rods was inspected visually under fluorescent light.

[0110] The testing conditions for the initial indium phosphide single crystal wafers doped with zinc and magnesium are as follows: visual inspection shows that the single crystal wafer is intact and has no cracks on the surface to be considered qualified.

[0111] The dislocation density of indium phosphide single crystals was determined using the method described in GB / T20230-2022 "Indium Phosphide Single Crystals".

[0112] The zinc and magnesium contents in indium phosphide single crystals are determined using the method specified in the following standard: "DB35 / T 1146-2011 Determination of Impurity Element Content in Silicon Materials by Glow Discharge Mass Spectrometry".

[0113] Carrier concentration was measured using a Hall instrument.

[0114] Preparation of indium phosphide single crystal rods doped with zinc and magnesium

[0115] The indium phosphide single crystal rods doped with zinc and magnesium in the following examples are 4-inch in diameter. However, indium phosphide single crystal rods doped with zinc and magnesium in other diameter sizes can also be prepared using the method of this application.

[0116] Indium phosphide single crystal rods doped with zinc and magnesium were prepared according to the following steps.

[0117] Six kilograms of polycrystalline indium phosphide and a small amount of 6N high-purity red phosphorus were mixed with the amounts of magnesium-containing and zinc-containing dopants listed in Table 1, and then placed together with 0.2 kilograms of boron oxide sealant into a crucible containing seed crystals. The crucible was placed inside a growth tube, and the mixture was kept under a vacuum of less than 10... -3 A vacuum-sealed growth tube was used. The growth tube was placed in a crystal growth furnace and heated using a multi-temperature zone system. The crucible was heated at a rate of 20 °C / min, raising the temperature to 1100 °C, melting the raw materials in the crucible and holding it for 4 hours. The resulting melt in the crucible was cooled, while simultaneously controlling the temperature gradient of the melt at 2.5 °C / cm and the cooling rate at 0.4 °C / h, allowing the melt to crystallize and grow an indium phosphide single crystal rod doped with zinc and magnesium when in contact with the seed crystal. After the single crystal growth was completed, the indium phosphide single crystal rod doped with zinc and magnesium was cooled to room temperature. After cooling to room temperature, the single crystal rod was removed from the crucible, yielding an InP single crystal rod with a diameter of 105 mm. Additionally, an indium phosphide single crystal rod for the comparative example was prepared using a similar method and parameters, but with adjustments to the amount of raw materials.

[0118] The experimental data in Table 1 show that the yield is low when magnesium or zinc is doped alone, and the dislocation density is high when magnesium is doped alone. However, when zinc and magnesium are doped simultaneously, the dislocation density is significantly lower than that of the crystal doped with magnesium alone, and is on par with that of the crystal doped with zinc alone. However, when zinc and magnesium are doped simultaneously at the specified concentrations (zinc: 0.5 ppm to 500 ppm, magnesium: 0.5 ppm to 1000 ppm), the yield is significantly improved. In addition, the data from Comparative Example 4 shows that when zinc and magnesium are doped simultaneously, but the magnesium and / or zinc content is not within the specified range (zinc: 0.5 ppm to 500 ppm, magnesium: 0.5 ppm to 1000 ppm), the effect on improving the yield is not significant. The data from Examples 1 to 4 show that when zinc and magnesium are doped simultaneously, the improvement in yield is most significant when the zinc content in the indium phosphide crystal is greater than or equal to 10 ppm and less than or equal to 150 ppm, and the magnesium content in the indium phosphide crystal is greater than or equal to 2 ppm and less than or equal to 200 ppm, more preferably less than or equal to 180 ppm.

[0119] Conclusion: Using zinc (0.5 ppm to 500 ppm) and magnesium (0.5 ppm to 1000 ppm), or a more preferred range of magnesium and zinc, results in lower dislocation density and higher yield than magnesium-only doping, and also higher yield than zinc-only doping. When indium phosphide crystals contain 0.5 ppm to 500 ppm zinc and 0.5 ppm to 1000 ppm magnesium, dislocation density can be reduced, twin defects reduced, and indium phosphide crystal yield improved while maintaining the required carrier concentration range. The improvement in yield is particularly significant when the zinc content is within the required carrier concentration range and the magnesium content is in the range of 2 to 200 ppm.

[0120] Preparation of indium phosphide single crystal wafers doped with zinc and magnesium

[0121] The zinc- and magnesium-doped indium phosphide single crystal rods prepared in the above embodiments are cut into zinc- and magnesium-doped indium phosphide single crystal wafers according to the following steps.

[0122] Cutting: The zinc and magnesium-doped indium phosphide single crystal rods are cut into initial single crystal wafers of zinc and magnesium-doped indium phosphide with a thickness of 800 μm using a multi-wire dicing machine. Figure 2 shows a schematic diagram of the single crystal rod fixing device used in the single crystal wafer preparation of this application; wherein the zinc and magnesium-doped indium phosphide single crystal rods 8 are fixed by a fixing device that partially surrounds graphite 9, so as to facilitate their separation from the single crystal wafer in subsequent steps. During the cutting process, the circular zinc and magnesium-doped indium phosphide single crystal rods are fixed using a semi-surrounded graphite. After cutting, the initial single crystal wafers of zinc and magnesium-doped indium phosphide are manually removed, and the operation is performed by the same person under the same conditions.

[0123] Chamfering: A chamfering machine is used to chamfer the edges of each circular single crystal wafer, making its edge cross-section curved.

[0124] Fixation: Place one side of the single crystal wafer on a 5.2 cm diameter, 250 μm thick, flat ceramic plate (Ra < 0.5 μm), and apply gentle pressure to ensure there are no air bubbles between the single crystal wafer and the ceramic plate.

[0125] Surface treatment: The ceramic plate carrying the single crystal wafer is placed in an etching solution at 35°C for 12 seconds. The etching solution consists of 1 mol% NH3, 10 mol% hydrogen peroxide, and the balance is water.

[0126] Polishing: Then, place the ceramic plate carrying the single crystal wafer in the support pad cavity of the polishing machine (close to the ceramic plate) and fix it. First, use the coarse polishing solution shown in Table 3 on the polishing equipment and polish for 60 minutes under the coarse polishing conditions shown in Table 2. After cleaning with deionized water (resistivity greater than 17.5 megohms × cm - value at 25°C), dry it. Then, use the fine polishing solution shown in Table 3 on the polishing equipment and polish for 6 minutes under the fine polishing conditions shown in Table 3. Then, take out the ceramic plate carrying the single crystal wafer and place it on a heating furnace to melt the adhesive. Remove the single crystal wafer from the ceramic plate, clean it with deionized water, and dry it.

[0127] Cleaning: a) Immerse the wafer in an aqueous solution containing 0.3 wt% NH3 and 1.3 wt% (unless otherwise stated, all solutions below are by weight percentage based on the total weight of the solution) of hydrogen peroxide for 5 minutes at 10°C; b) Rinse the wafer surface with deionized water for 3 minutes at 10°C; c) Immerse the wafer in a 10 wt% hydrogen peroxide solution for 5 minutes at 20°C; d) Rinse the wafer surface with deionized water for 3 minutes at 15°C; e) Immerse the wafer in a 10 wt% ammonia solution for 5 minutes at 20°C; f) Rinse the wafer surface with deionized water for 3 minutes at 15°C; g) Dry the wafer in a wafer rotary dryer with hot nitrogen.

[0128] The thickness of the obtained indium phosphide single wafer is 650 μm. The performance test results of the indium phosphide single wafers of each embodiment are shown in Table 4 below, where the carrier concentration was tested using a Hall instrument.

[0129] Table 2 Composition of the coarse polishing solution and polishing conditions

[0130] Table 3 Composition of the fine polishing solution and polishing conditions

[0131] Table 4 Performance test results of indium phosphide single crystal wafers

[0132] The data in Table 4 show that the InP single crystal wafers cut from zinc- and magnesium-doped indium phosphide single crystal rods prepared according to Examples 1 to 4 of this application have the characteristics of high carrier density and low dislocation density, which meet the requirements of industrial applications such as optoelectronic devices and electronic devices.

[0133] While the foregoing descriptions have referenced specific embodiments of this application, those skilled in the art should understand that modifications can be made to the described embodiments without departing from the principles and spirit of this application. The scope of this application is defined by the appended claims. All foregoing references, including papers, patent documents, and standards, are incorporated herein by reference in their entirety.

Claims

1. An indium phosphide crystal, which is a P-type indium phosphide single crystal, wherein the indium phosphide crystal contains 0.5 ppm to 500 ppm of zinc and 0.5 ppm to 1000 ppm of magnesium.

2. The indium phosphide crystal according to claim 1, wherein the zinc content is 0.8 ppm to 500 ppm, preferably 1 ppm to 400 ppm, more preferably 1.2 ppm to 300 ppm.

3. The indium phosphide crystal according to claim 1 or 2, wherein the magnesium content is 0.8 ppm to 800 ppm, preferably 1 ppm to 500 ppm, more preferably 2 ppm to 300 ppm.

4. The indium phosphide crystal according to any one of claims 1 to 3, wherein the carrier concentration of the indium phosphide crystal is 1 × 10⁻⁶. 17 cm -3 Up to 5×10 19 cm -3 For example, 1×10 18 cm -3 Up to 1×10 19 cm -3 1×10 is preferred 18 cm -3 Up to 8×10 18 cm -3 Or, for example, 8×10 17 cm -3 Up to 9×10 18 cm -3 9×10 is preferred 17 cm -3 Up to 7×10 18 cm -3 .

5. The indium phosphide crystal according to any one of claims 1 to 4, wherein the indium phosphide crystal is in the form of an indium phosphide single crystal rod.

6. A method for preparing indium phosphide crystals, wherein the indium phosphide crystals are p-type indium phosphide single crystals, the method comprising the step of placing phosphorus, polycrystalline indium phosphide, a dopant containing magnesium, and a dopant containing zinc or a dopant containing both zinc and magnesium, together with a sealant, into a growth container, such as a crucible, containing a seed crystal; and The step of placing the container in a crystal growth furnace and heating it to a temperature above the melting point of indium phosphide.

7. The method according to claim 6 further includes the step of gradually cooling the melt in the container to obtain the P-type indium phosphide single crystal.

8. The method according to claim 6 or 7, wherein the step of placing the container in a crystal growth furnace and heating it to a temperature above the melting point of indium phosphide comprises: The container is placed in a crystal growth furnace and heated using a multi-temperature zone system. Preferably, a temperature gradient of 0.1 to 10.0 °C / cm is established in the single crystal growth zone to raise the temperature and maintain it above the melting point of indium phosphide.

9. The method according to any one of claims 6 to 8, wherein the content of zinc in the obtained indium phosphide crystal is from 0.5 ppm to 500 ppm, and the content of magnesium in the obtained indium phosphide crystal is from 0.5 ppm to 1000 ppm.

10. The method according to any one of claims 6 to 9, wherein The magnesium-containing dopant is selected from magnesium, magnesium phosphides, magnesium-indium alloys, or any mixture thereof; The zinc-containing dopant is selected from zinc, zinc phosphides, zinc-indium alloys, or other zinc-containing materials. A mixture of the above substances.

11. The method according to any one of claims 6 to 10, wherein the method is selected from the vertical Bridgman process (VB), vertical gradient condensation (VGF), vapor pressure controlled Czochralski (VCZ), or vertical crucible growth.

12. The use of a combination of magnesium-containing dopants and zinc-containing dopants, or dopants containing zinc and magnesium, in the preparation of indium phosphide crystals to increase carrier concentration while reducing dislocation density, reducing twin defects, and / or increasing the yield of indium phosphide crystals.

13. An indium phosphide single crystal wafer, made from indium phosphide crystals according to any one of claims 1 to 5 or from indium phosphide crystals obtained by the method according to any one of claims 6 to 11.

14. The indium phosphide single wafer of claim 13, wherein the single wafer is used for epitaxial growth thereon or for further fabrication of devices, the devices including optoelectronic devices, such as lasers, detectors, light-emitting diodes, etc., or electronic devices, such as HBTs, MESFETs, PHEMTs, etc.

15. An electronic or optoelectronic device made of or containing components made of an indium phosphide single wafer according to any one of claims 13 to 14.

16. The optoelectronic device according to claim 15, wherein it is a laser, a detector, or a light-emitting diode, etc.

17. The electronic device according to claim 15, wherein it is an HBT, a MESFET, or a PHEMT, etc.

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