Indium phosphide crystal containing sulfur and tin, single crystal wafer, preparation method for indium phosphide crystal, and device

Abstract

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

Description

Indium phosphide crystal containing sulfur and tin, single crystal, preparation method and device thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202410178125.7, filed on February 8, 2024, entitled “Indium phosphide crystals, single crystal crystals containing sulfur and tin, and methods and devices for preparing the same,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of semiconductor processing and manufacturing, and in particular to an indium phosphide crystal and a preparation method thereof; it also relates to an indium phosphide single crystal wafer made from the indium phosphide crystal and a preparation method thereof, as well as a device comprising the indium phosphide crystal. Background Art

[0004] Indium phosphide (InP), a III-V compound semiconductor material, boasts higher electron mobility than materials like silicon and gallium arsenide. It also boasts high photoelectric conversion efficiency, strong radiation resistance, and high thermal conductivity. These excellent properties have led to its widespread application in a variety of fields, including integrated circuits, high-speed and high-frequency devices, optoelectronic devices, and fiber-optic communications.

[0005] The manufacture of InP single crystal wafers usually includes the steps of growing single crystals, cutting rough wafers from single crystal rods, edging the rough wafers, grinding, rough polishing, fine polishing, cleaning, drying, etc. In order to broaden the scope of application of indium phosphide single crystal wafers and improve their performance, doping is usually adopted to obtain the electrical properties required for the application, such as carrier concentration, resistivity, etc. The doping elements include sulfur, tin, zinc, iron, etc. Among them, the doping of sulfur or tin obtains N-type InP single crystal wafers with high carrier concentration, the doping of zinc obtains P-type InP single crystal wafers with high carrier concentration, and the doping of iron obtains semi-insulating InP single crystal wafers. However, in the growth process of the above two semiconducting indium phosphide single crystals (i.e., P-type InP single crystal and N-type InP single crystal), it is still inevitable to face the problem of low stacking fault energy of indium phosphide crystals. Due to its low stacking fault energy, twins are easily generated during the growth process, and the dislocation density is high, usually reaching hundreds, thousands or even tens of thousands of levels (cm -2 ), which will seriously affect the yield of indium phosphide crystals.

[0006] Summary of the Invention

[0007] Therefore, the prior art requires an InP crystal having a low dislocation density, no twin defects, and good conductive properties, and a preparation method thereof.

[0008] The present application is proposed to solve the above problems. It reduces the dislocation density and the formation of defects such as twins by simultaneously doping two or more doping elements into the indium phosphide crystal growth melt, thereby improving the yield of indium phosphide single crystals.

[0009] Specifically, the first aspect of the present application provides an indium phosphide crystal, which is an N-type indium phosphide single crystal. The indium phosphide crystal contains 0.5ppm to 500ppm of sulfur (S) and 0.5ppm to 1000ppm of tin (Sn).

[0010] On the other hand, the present application provides a method for preparing indium phosphide crystals, the method comprising the steps of placing phosphorus, indium phosphide polycrystals, a dopant containing sulfur, a dopant containing tin, and a sealant into a growth container, such as a crucible, provided with a seed crystal; and placing the container in a crystal growth furnace and heating it to a temperature above the melting point of indium phosphide; preferably, the sulfur content in the obtained indium phosphide crystals is 0.5 ppm to 500 ppm, and the tin content is 0.5 ppm to 1000 ppm.

[0011] In another aspect, the present application provides an indium phosphide single crystal wafer, which is made of the above-mentioned N-type indium phosphide crystal or the N-type indium phosphide crystal obtained according to the above-mentioned method.

[0012] In another aspect, the present application provides an electronic device or optoelectronic device, which is made of the above-mentioned indium phosphide single crystal wafer or contains components made of the above-mentioned indium phosphide single crystal wafer.

[0013] On the other hand, the present application provides the use of a combination of a sulfur-containing dopant and a tin-containing dopant, or a dopant containing sulfur and tin, in the preparation process of indium phosphide crystals for increasing the carrier concentration while reducing dislocation density, reducing twin defects, and / or improving the yield of indium phosphide crystals.

[0014] The N-type indium phosphide crystal doped with both sulfur and tin obtained in the present application has a low dislocation density and reduces the formation of twins. Therefore, the indium phosphide crystal has a high yield and can obtain single crystals with uniform and stable performance. At the same time, the obtained N-type indium phosphide crystal has good electrical conductivity and can be used in optoelectronic devices such as lasers and photodetectors, electronic devices such as transistors, and high-frequency components. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a cross-sectional view of one embodiment of a crystal growth apparatus including a sealed container for growing a sulfur- and tin-doped indium phosphide single crystal.

[0016] FIG2 is a schematic diagram of a single crystal rod fixing device used in the preparation of a single crystal wafer in the present application. DETAILED DESCRIPTION

[0017] In order to make the invention purpose, technical solution and beneficial technical effect of this application clearer, this application is described in detail below with reference to specific embodiments. It should be understood that the embodiments described in this specification are only for explaining this application and are not intended to limit this application.

[0018] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value can serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0019] Unless otherwise specified, all embodiments and preferred embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0020] Unless otherwise specified, all technical features and optional technical features or preferred technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0021] As mentioned above, the present application provides an indium phosphide crystal, which is an N-type indium phosphide single crystal. The indium phosphide crystal contains 0.5ppm to 500ppm of sulfur and 0.5ppm to 1000ppm of tin.

[0022] Although sulfur and tin are commonly used doping elements to form N-type indium phosphide crystals in the prior art, they are typically used alone, and there have been no reports of sulfur / tin co-doped indium phosphide crystals. While there are occasional reports of indium phosphide crystals containing both sulfur and tin, these crystals are typically composed primarily of one element, with the other present as a trace impurity, and the proportions of the two elements differ significantly.

[0023] Without being bound by any theory, the inventors have found that:

[0024] (1) In actual crystal growth, sulfur has a significant impurity hardening effect in InP. Doping a certain amount of sulfur can effectively strengthen the lattice strength of the InP crystal, thereby greatly reducing the point defect density of the InP crystal. However, sulfur-doped InP is prone to twinning during crystal growth, resulting in a low single crystal rate, which is also a reason for the high cost of InP single crystals. In recent years, the market has placed increasingly high demands on the carrier concentration of N-type InP crystals, which requires the addition of more sulfur-containing dopants during the InP crystal growth process. This also greatly increases the probability of twinning during the InP crystal growth process, greatly reducing the single crystal rate of the crystal.

[0025] (2) In the actual production process, it was found that the addition of tin as an N-type dopant can inhibit the formation of twins to a certain extent. This may be because the introduction of tin increases the viscosity of the melt during the growth of InP crystals, which is beneficial to the stability of the InP hot melt. However, tin has little effect on strengthening the lattice strength, so that the point defect density of tin-doped InP crystals is relatively high, reaching hundreds or even thousands (cm -2 ), and due to the low segregation coefficient of tin in the InP crystal growth process, it is difficult to grow InP crystals with high carrier concentrations, especially at the head of the crystal rod (according to the article "Crystal growth and properties of group IV doped indium phosphide" published by JB Mullin et al., Journal of Crystal Growth, 13 / 14 (t972) 640-646, North-Holland Publishing Co., the segregation coefficient of Sn in InP crystals is 2.1E-2). In order to meet the market demand for high carrier concentrations, a large amount of dopant containing tin must be added. Even so, it is difficult to grow a crystal that meets market demand at the head of the crystal, and the high tin content basically remains at the tail, which will damage the single crystal formation of the InP crystal to a certain extent.

[0026] (3) In the present application, sulfur and tin are used as N-type dopants in a certain ratio and are co-doped into indium phosphide crystals, which can not only reduce the dislocation density of the crystal, but also inhibit the formation of twins to a certain extent, that is, there is a certain degree of synergistic effect, which can effectively improve the crystallization rate (yield rate) of single crystals; and by adjusting the doping ratio, the application requirements of low dislocation density and high carrier concentration can be fully met.

[0027] Herein, "segregation coefficient", also known as effective distribution coefficient, refers to the fact that at the solid-liquid interface, the solubility of impurities in different phases is different, so the concentration of impurities distributed in the materials on both sides of the interface is different. The segregation coefficient is represented by K, K = (solubility of impurities in the solid phase) / (solubility of impurities in the liquid phase) (K = Cs / Cl). The segregation coefficient of each element can be determined by a person skilled in the art using methods known in the art. For example, the segregation coefficient of an element can be determined according to the method described in the article "Growth and Properties of Sulfur-Doped Low Dislocation Indium Phosphide Single Crystals" published by Fang Dunfu et al. (Journal of Applied Sciences, Vol. 1, No. 3, July 1983).

[0028] In some embodiments of the present application, the content of sulfur element in the indium phosphide crystal can be 0.5ppm to 500ppm; for example, the doping amount of the sulfur element can be 0.5ppm, 0.8ppm, 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 10ppm, 20ppm, 40ppm, 50ppm, 80ppm, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, etc., or within any content range consisting of any of the above contents or any contents disclosed in the examples of the present application as end values.

[0029] In some embodiments of the present application, the content of tin element in the indium phosphide crystal can be 0.5ppm to 1000ppm; for example, the doping amount of the tin element can be 0.5ppm, 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, 9ppm, 10ppm, 20ppm, 40ppm, 50ppm, 80ppm, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 800ppm, 1000ppm, etc., or within any content range consisting of any of the above contents or any contents disclosed in the examples of the present application as end values.

[0030] In some embodiments of the present application, in addition to sulfur and tin, the indium phosphide crystal may also contain other elements added or doped for other purposes, such as iron (Fe).

[0031] It should be noted that the indium phosphide crystals provided herein are typically in the form of single crystal rods. For single crystal rod-shaped indium phosphide crystals, it has been found that the doping element content (which is directly proportional to the carrier concentration CC) varies at different cross-sections along the growth direction of the single crystal rod, primarily related to the segregation coefficient K of the doping element (impurity element) in the indium phosphide.

[0032] The following formula gives the distribution relationship of the doping element content in the crystal rod (according to Pfann, WG, "Zone Melting"). x =K·C0(1-X) (K-1)

[0033] Among them C x is the solubility of the doping element in the solid phase at different cross sections; X is the ratio of the length of the crystallized part to the total length of the crystal; C0 is the solubility of the doping element in the liquid phase in the molten state before crystallization.

[0034] Specifically, the distribution of dopant sulfur and tin (k < 1) in the indium phosphide crystal is non-uniform; their content increases nonlinearly from the beginning of the ingot growth to the end of the crystal. Therefore, when the indium phosphide crystal is in the form of a single crystal ingot, or in other situations where the dopant element is non-uniformly distributed within the indium phosphide crystal, the ranges specified in this application for the dopant element content in the indium phosphide crystal should be understood as requiring that the dopant element content at any location within the finished single crystal ingot (excluding the very end and very end of the single crystal ingot, which should be discarded during processing) falls within the specified range.

[0035] The indium phosphide crystal provided herein may also be in the form of a single crystal wafer. Such a single crystal wafer can be obtained, for example, by slicing an indium phosphide single crystal rod. When the indium phosphide crystal is in the form of a single crystal wafer, the type of doping element in the indium phosphide crystal and the content of the doping element in the crystal are also as described above.

[0036] The indium phosphide crystal of the present application is an N-type indium phosphide single crystal. In some preferred embodiments of the present application, the carrier concentration of the indium phosphide single crystal is 1×10 17 cm -3 to 5×10 19 cm -3 , for example, 1×10 18 cm -3 to 1×10 19 cm -3 , preferably 1×10 18 cm -3 to 8×10 18 cm -3 , or 1×10 17 cm -3 to 9×10 17 cm -3 , preferably 3×10 17 cm -3 to 5×10 17 cm -3 .

[0037] Herein, carrier concentration refers to the 3) is equal to the concentration of ionized impurities at room temperature without compensation. The carrier concentration can be determined using methods known in the art, such as a Hall instrument.

[0038] The dislocation density of the indium phosphide single crystal of the present application is low and the dislocation distribution is very uniform. In some preferred embodiments of the present application, the average dislocation density of the indium phosphide crystal can be 800 / cm 2 Below, or 500 / cm 2 Below, or 100 / cm 2 Below, even 50 / cm 2 the following.

[0039] In the present application, the dislocation density of the sulfur- and tin-doped indium phosphide single crystal is measured using the method described in GB / T20230-2022 "Indium Phosphide Single Crystal".

[0040] On the other hand, the present application provides a method for preparing indium phosphide crystals, which includes the steps of placing phosphorus, indium phosphide polycrystals, a dopant containing sulfur, and a dopant containing tin, or a dopant containing sulfur and tin, together with a sealant, into a growth container (e.g., a crucible) provided with a seed crystal; and placing the container in a crystal growth furnace and heating it to a temperature above the melting point of indium phosphide. Preferably, the content of sulfur in the indium phosphide crystal is 0.5ppm~500ppm, for example, 0.5ppm, 0.8ppm, 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 10ppm, 20ppm, 40ppm, 50ppm, 80ppm, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, etc.; at the same time, preferably, the content of tin in the indium phosphide crystal is 0.5ppm~1000ppm, for example, 0.5ppm, 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, 9ppm, 10ppm, 20ppm, 40ppm, 50ppm, 80ppm, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 800ppm, 1000ppm, etc., or within any content range consisting of any of the above relative amounts or any relative amounts disclosed in the examples of the present application as end values.

[0041] In this application, the content of sulfur and tin in indium phosphide crystals is measured by glow discharge mass spectrometry (GDMS). In a glow discharge ion source, a potential difference is applied between the cathode (sample to be analyzed) and the anode, and the plasma is maintained by introducing an inert gas (usually argon). The inert gas ions and fast neutral substances formed in the plasma are attracted to the surface of the sample, and their collision causes the surface to sputter and produce neutral substances. These neutral particles diffuse into the plasma, are then ionized in the equipotential region of the plasma, and can then be extracted into a mass spectrometer for quantitative analysis. For example, the current detection standard, "DB35 / T 1146-2011 Determination of impurity element content in silicon materials by glow discharge mass spectrometry", can be used for reference.

[0042] Herein, the term "dopant" is used to refer to a substance used to provide elements such as sulfur or tin in the preparation process of indium phosphide crystals; sulfur or tin can be used as simple substances, or sulfur-containing compounds and / or tin-containing compounds containing sulfur or tin that are suitable for industrial production environments can be used. For example, in some preferred embodiments of the present application, the dopant containing sulfur element is sulfur, indium sulfide (In2S3 and / or In2S), or a mixture thereof. For example, in some preferred embodiments of the present application, the dopant containing tin element is selected from tin, tin phosphide, an alloy of tin and indium, or a mixture of the above substances. In addition, sulfur and tin can also be present in the same dopant, in which case the dopant is both a sulfur-containing dopant and a tin-containing dopant. The dopant used in the present application is preferably of high purity, preferably with a purity of 99.00% or above, for example 99.99% or above.

[0043] In the present application, the equipment used in the indium phosphide crystal preparation method (such as a growth container, a furnace, etc.) can use conventional equipment that is well known or commonly used in the art for preparing N-type indium phosphide single crystals or P-type indium phosphide single crystals.

[0044] In the present application, the raw materials phosphorus, indium phosphide polycrystal, dopant, and sealant used in the indium phosphide crystal preparation method can all be conventional raw materials known in the art for preparing N-type indium phosphide single crystals or P-type indium phosphide single crystals, and can be prepared independently or obtained through commercial channels. These raw materials are generally high-purity, preferably having a purity of 99.00% or higher, for example, 99.99% or higher.

[0045] In the present application, the operation of adding phosphorus, indium phosphide polycrystals, sulfur-containing dopants, tin-containing dopants, or dopants containing sulfur and tin, and a sealant into a growth vessel can be implemented in a variety of ways. For example, phosphorus, indium phosphide polycrystals, sulfur-containing dopants, tin-containing dopants, or dopants containing sulfur and tin, and a sealant can be added to the growth vessel simultaneously or sequentially. Alternatively, the sulfur-containing dopants and / or tin-containing dopants or dopants containing sulfur and tin can be pre-mixed into the indium phosphide polycrystals (or dopants can be introduced during the preparation of the indium phosphide polycrystals to form indium phosphide polycrystals containing doping elements) and then added to the growth vessel, etc. All of these implementations can be used to prepare the indium phosphide crystals of the present application. On this basis, those skilled in the art can also conceive of other equivalent implementations, and all of the above implementations and other equivalent implementations are considered to be within the scope of the disclosure of the present application.

[0046] In some preferred embodiments of the present application, the amount of the sulfur-containing dopant, the tin-containing dopant, or the dopant containing sulfur and tin is such that the content of the sulfur element in the indium phosphide crystal is 0.5 ppm to 500 ppm, and the content of the tin element in the indium phosphide crystal is 0.5 ppm to 1000 ppm, and more preferably the carrier concentration of the obtained indium phosphide single crystal rod within the effective length is 1×10 17 cm -3 to 5×10 19 cm - 3 , preferably 1×10 18 cm -3 to 1×10 19 cm -3 .

[0047] In some embodiments, the method for preparing indium phosphide crystals further comprises:

[0048] The step of gradually cooling the melt in the container to obtain an N-type indium phosphide single crystal.

[0049] 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 a 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 increase the temperature and maintain it above the melting point of indium phosphide; and then gradually cooling the melt in the container to obtain an N-type indium phosphide single crystal.

[0050] The amounts of the raw material phosphorus, indium phosphide polycrystal, dopant and sealant used in the indium phosphide crystal preparation method of the present application can be determined by those skilled in the art according to actual needs.

[0051] In some preferred embodiments of the present application, the method for preparing the crystal is selected from the vertical Bridgman method (VB), the vertical gradient condensation method (VGF), the vapor pressure controlled Czochralski method (VCZ) or the vertical crucible growth method.

[0052] In some preferred embodiments of the present application, the method for preparing crystals is selected from the vertical gradient condensation method (VGF), in which the crucible can move in the temperature field, or the crucible can remain stationary while the temperature field changes.

[0053] In some preferred embodiments of the present application, a vertical gradient condensation method (VGF) is used, the steps of which include:

[0054] 1) Phosphorus, indium phosphide polycrystal, a dopant containing sulfur, a dopant containing tin, or a dopant containing sulfur and tin, together with boron oxide as a sealant, are placed in a crucible provided with a seed crystal;

[0055] 2) placing the crucible described in step 1) in a growth tube (preferably a quartz tube, but other types of growth tubes may also be used) and sealing the growth tube under vacuum;

[0056] 3) placing the growth tube with the sealed crucible from step 2) into a 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 ingot growth zone), raising the temperature to and maintaining it above the melting point of indium phosphide;

[0057] 4) gradually cooling the melt in the crucible obtained in step 3) to obtain an N-type indium phosphide single crystal containing sulfur and tin.

[0058] The container for growing indium phosphide single crystal ingots can be made of a suitable crucible material, such as a pyrolytic boron nitride (PBN) crucible. The container or crucible for single crystal growth comprises a cylindrical main body with a diameter slightly larger than the diameter of the sulfur- and tin-doped indium phosphide single crystal ingot to be produced. At the bottom is a small-diameter seed crystal (also called a seed crystal) recess, separated by a conical transition zone. The seed crystal recess is used to hold the cylindrical seed crystal used in the production of indium phosphide single crystals.

[0059] The crystal orientation of the upper end face of the seed crystal is the desired surface crystal orientation of the sulfur- and tin-doped indium phosphide single crystal substrate, for example, (100) or a surface crystal orientation that is deflected to a certain angle to an adjacent crystal axis relative to the (100) crystal orientation.

[0060] As shown in Figure 1, a suitable sealant 5 (such as boron oxide) is placed into a crucible 4 along with raw materials 6, including phosphorus, indium phosphide polycrystals, and a sulfur-containing dopant, a tin-containing dopant, or a dopant containing both sulfur and tin. The sealant inhibits the decomposition of the indium phosphide material at high temperatures and also serves to isolate the inner wall of the crucible from the melt or the surface of the solid single crystal rod during single crystal growth. This reduces adhesion between the surface of the growing single crystal rod and the inner wall of the crucible, making it easier to obtain a complete sulfur- and tin-doped indium phosphide single crystal rod. The amount of sealant used is conventional in the art.

[0061] According to the above preparation method of the present application, the indium phosphide crystal according to the first aspect of the present application can be obtained, wherein the indium phosphide crystal is a sulfur / tin dual-doped N-type indium phosphide single crystal.

[0062] Another aspect of the present application provides the use of a combination of a sulfur-containing dopant and a tin-containing dopant, or a dopant containing both sulfur and tin, for increasing carrier concentration while simultaneously reducing dislocation density, reducing twin defects, and / or improving the yield of indium phosphide crystals during the preparation of indium phosphide crystals. In a preferred embodiment, the sulfur content of the resulting indium phosphide crystals is 0.5 ppm to 500 ppm, and the tin content is 0.5 ppm to 1000 ppm.

[0063] The present application also provides an indium phosphide single crystal, which is made from the above-mentioned N-type indium phosphide single crystal or from the N-type indium phosphide single crystal obtained according to the above-mentioned method. The indium phosphide single crystal can be made using the above-mentioned N-type indium phosphide single crystal or from the N-type indium phosphide single crystal obtained according to the above-mentioned method using conventional methods in the art. The sulfur- and tin-doped indium phosphide single crystal rod of the present application can be cut to produce sulfur- and tin-doped indium phosphide single crystals. The industrial preparation method generally includes the steps of cutting rough crystals from the single crystal rod, edging the rough crystals, grinding, rough polishing, fine polishing, cleaning, and drying.

[0064] 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 in other shapes (such as an irregular circle, square, rectangle, etc.), it refers to the diameter of a circle drawn with the center of the single wafer as the center, so that the circle includes all parts of the single wafer.

[0065] In the present application, the term "effective length" means the actual length of a single crystal rod that can be used to cut into single crystal wafers.

[0066] The thickness of the sulfur- and tin-doped indium phosphide single crystal wafer of the present application is 200 to 2000 μm, preferably 300 to 1200 μm.

[0067] The sulfur- and tin-doped indium phosphide single crystal wafers of the present application are produced by slicing sulfur- and tin-doped indium phosphide single crystal rods. The sulfur- and tin-doped indium phosphide single crystal rods are single crystal rods with a circular transverse cross-section (hereinafter referred to as round single crystal rods). The diameter of the circular cross-section is generally no more than 12 inches, and preferably 1 to 8 inches. Of course, the sulfur- and tin-doped indium phosphide single crystal rods may also be single crystal rods with other transverse cross-section shapes, such as a sulfur- and tin-doped indium phosphide single crystal rod with a square (square or rectangular) transverse cross-section obtained by processing a round single crystal rod. In this case, the sliced ​​wafers are non-circular sulfur- and tin-doped indium phosphide single crystal wafers.

[0068] The sulfur- and tin-doped indium phosphide single crystal wafers of the present application are preferably cut from single crystal ingots produced by the method for producing sulfur- and tin-doped indium phosphide single crystal ingots described herein. The processing of the sulfur- and tin-doped indium phosphide single crystal wafers of the present application is identical to that of conventional sulfur-doped single crystals. Specific examples of the processing methods of the sulfur- and tin-doped indium phosphide single crystal wafers of the present application can be found in Chinese Patent No. CN 116043318A, the contents of which are incorporated herein by reference.

[0069] The indium phosphide single crystal wafer described in this application can be used for epitaxial growth thereon or further processed into devices, including but not limited to optoelectronic devices such as lasers, detectors, light-emitting diodes, etc., or electronic devices such as HBT, MESFET, PHEMT, etc.

[0070] In another aspect, the present application provides an electronic device or optoelectronic device made from the above-mentioned indium phosphide single crystal wafer or containing components made from the above-mentioned indium phosphide single crystal wafer. The optoelectronic device includes, for example, a laser, a detector, a light-emitting diode, etc., and the electronic device includes, for example, an HBT, a MESFET, a PHEMT, etc.

[0071] This application can be illustrated by the following implementation scheme:

[0072] 1. An indium phosphide crystal, which is an N-type indium phosphide single crystal, wherein the indium phosphide crystal contains 0.5 ppm to 500 ppm of sulfur and 0.5 ppm to 1000 ppm of tin.

[0073] 2. The indium phosphide crystal according to embodiment 1, wherein the sulfur content is 0.5 ppm to 500 ppm, preferably 0.8 ppm to 400 ppm, and more preferably 1 ppm to 300 ppm.

[0074] 3. The indium phosphide crystal according to embodiment 1 or 2, wherein the tin element content is 0.5 ppm to 1000 ppm, preferably 1 ppm to 500 ppm, and more preferably 2 ppm to 300 ppm.

[0075] 4. The indium phosphide crystal according to embodiments 1 to 3, wherein the carrier concentration of the indium phosphide crystal is 1×10 17 cm -3 to 5×10 19 cm -3 , for example 1×10 18 cm -3 to 1×10 19 cm -3 , preferably 1×10 18 cm -3 to 8×10 18 cm -3 , or for example 1×10 17 cm -3 to 9×10 17 cm -3 , preferably 3×10 17 cm -3 to 5×10 17 cm -3 .

[0076] 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.

[0077] 6. A method for preparing an N-type indium phosphide single crystal, the method comprising the steps of placing phosphorus, an indium phosphide polycrystal, a dopant containing sulfur, a dopant containing tin, or a dopant containing sulfur and tin, together with a sealant, into a growth container, such as a crucible, provided with a seed crystal;

[0078] and placing the container into a crystal growth furnace and heating the container to a temperature above the melting point of indium phosphide.

[0079] 7. The method according to embodiment 6 further includes the step of gradually cooling the melt in the container to obtain the N-type indium phosphide single crystal.

[0080] 8. The method according to embodiment 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 includes: placing the container in a 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, so that the temperature is increased and maintained above the melting point of indium phosphide.

[0081] 9. The method according to any one of embodiments 6 to 8, wherein the content of sulfur in the obtained indium phosphide crystal is 0.5 ppm to 500 ppm, and the content of tin in the obtained indium phosphide crystal is 0.5 ppm to 1000 ppm.

[0082] 10. The method according to any one of embodiments 6 to 9, wherein

[0083] The dopant containing sulfur is selected from sulfur, indium sulfide, or a mixture thereof;

[0084] The dopant containing tin is selected from tin, tin phosphide, alloy of tin and indium, or a mixture thereof.

[0085] 11. The method according to any one of embodiments 6 to 10, wherein the method is selected from the vertical Bridgman method (VB), the vertical gradient condensation method (VGF), the vapor pressure controlled Czochralski method (VCZ) or the vertical crucible growth method.

[0086] 12. Use of a combination of a sulfur-containing dopant and a tin-containing dopant, or a dopant containing sulfur and tin, in an indium phosphide crystal preparation process for increasing carrier concentration while reducing dislocation density, reducing twin defects, and / or improving the yield of indium phosphide crystals.

[0087] 13. An indium phosphide single crystal sheet, made of the indium phosphide crystal according to any one of embodiments 1 to 5, or the indium phosphide single crystal obtained by the method according to any one of embodiments 6 to 11.

[0088] 14. An indium phosphide single crystal wafer according to embodiment 13, wherein the single crystal wafer is used for epitaxial growth thereon or is further made into a device, wherein the device includes an optoelectronic device, such as a laser, a detector, a light-emitting diode, etc., or an electronic device, such as an HBT, a MESFET, a PHEMT, etc.

[0089] 15. An electronic device or optoelectronic device, which is made of the indium phosphide single crystal wafer according to any one of Embodiments 13 to 14, or contains a component made of the indium phosphide single crystal wafer according to any one of Embodiments 13 to 14.

[0090] 16. The optoelectronic device according to embodiment 15, which is a laser, a detector, or a light emitting diode.

[0091] 17. The electronic device according to embodiment 15, which is an HBT, a MESFET, a PHEMT, or the like.

[0092] The indium phosphide crystal containing sulfur and tin obtained in the present application has few twins, low defect density, and high yield, which can greatly reduce costs and has good electrical properties, so it can be more widely used in optoelectronic devices such as lasers and photodetectors, as well as high-frequency electronic devices.

[0093] Example

[0094] For a better understanding of the present application, the present application will be described in detail below with reference to embodiments and drawings. However, it should be appreciated that these embodiments are merely illustrative of the present application and are not intended to limit the present application.

[0095] 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 according to conventional methods and can be used directly without further treatment. The instruments used in each example are all commercially available.

[0096] production equipment

[0097] Figure 1 shows a cross-sectional view of an example of a crystal growth apparatus comprising a sealed container for growing sulfur- and tin-doped indium phosphide single crystals. The apparatus is housed within a high-pressure chamber 1 and may include a growth tube 3 within a furnace. The 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, approximately 2 to 4 MPa. The temperature of each zone is adjusted to provide the temperature distribution and temperature gradient required to control melt solidification. The temperature distribution and temperature gradient within the furnace are adjusted to achieve the desired upward movement of the crystallization interface through the melt, for example, establishing a temperature gradient of 0.1 to 10°C / cm in the single crystal ingot growth zone and a lower temperature gradient at the seed end. A crucible 4 within the growth tube (quartz tube) 3 includes a seed well for storing a seed crystal 7. The single crystal grows along the top of the seed crystal 7. In one embodiment, the crucible 4 may be a pyrolytic boron nitride structure having a cylindrical crystal growth portion, a smaller diameter seed well cylinder, and a tapered transition portion. The crystal growth portion is open at the top of the crucible 4 and has a diameter equal to the diameter of the desired crystal product. In an exemplary embodiment, the seed well cylinder at the bottom of the crucible 4 may have a closed bottom and a diameter slightly larger than the seed crystal 7. The cylindrical crystal growth portion and seed well cylinder may have straight walls or taper outward gradually at approximately 1 to 30 degrees to facilitate removal of the crystal from the crucible 4.

[0098] Crucible 4 fits inside growth tube 3 with a narrow gap therebetween. Growth tube 3 is closed at the bottom in the seed well area and sealed at the top after the crucible and raw materials are loaded.

[0099] Because the growth tube-crucible assembly has a funnel shape, a growth tube support is required to accommodate this funnel shape and maintain the growth tube 3 stable and upright within the furnace. In other embodiments, the growth tube-crucible assembly can have different shapes, and the basic structure of the growth tube support will vary depending on the shape.

[0100] In the VGF crystal growth method, the crystallization temperature gradient of a fixed heat source is moved by electrical control while the crystal is fixed.

[0101] To implement vertical gradient condensation growth, the desired temperature gradient distribution must be established within the furnace. The power levels of the furnace's heating zones are individually controlled by a computer programmed to heat and cool the furnace to suit the crystallization temperature and temperature gradient requirements. For single crystal ingot production, for example, furnace temperature fluctuations may need to be controlled to <±1°C. During furnace preparation, phosphorus and indium phosphide polycrystalline feedstock 6, including dopants, is loaded into the growth tube 3.

[0102] In the embodiment, indium sulfide and tin are used as dopants. A (100) oriented seed crystal is placed in the crucible seed tank, and then the material is added. The raw material (containing an appropriate amount of dopant) is placed in the crucible, and the crucible is placed in the growth tube 3. The growth tube with the crucible is connected to the vacuum system for evacuation, and then the growth tube is sealed. The sealed growth tube is then placed in the furnace, as shown in Figure 1. The heating furnace is turned on to heat the growth tube and its contents to a temperature above 1050°C, the melting point of indium phosphide. The temperature gradient of the crystallization interface can be adjusted to 0.1 to 10°C / cm according to different positions of the single crystal rod. The entire temperature distribution is adjusted to give a crystallization rate of 2 to 5 mm / h.

[0103] The sulfur- and tin-doped indium phosphide single crystal rod grown using the above exemplary growth process parameters can be used for cutting wafers.

[0104] The designed growth program can obtain a suitable growth rate and a suitable temperature gradient near the solid-liquid interface from the seed end to the end of single crystal growth (or the entire melt solidifies and grows into a solid single crystal).

[0105] Under this growth procedure and the appropriate dopant content, single crystal growth is maintained throughout the entire length of the single crystal rod. For example, sulfur- and tin-doped indium phosphide single crystal rods with diameters of 2 to 6 inches can be grown.

[0106] After all the raw materials in the crucible have solidified, the grown single crystal rod is cooled to room temperature under temperature-controlled conditions.

[0107] Performance Testing

[0108] The appearance quality of the prepared sulfur- and tin-doped indium phosphide single crystal rod is inspected by visual inspection under a fluorescent lamp.

[0109] The inspection conditions of the prepared sulfur- and tin-doped indium phosphide single crystal initial wafers are as follows: the single wafer is considered qualified if it is visually intact and has no surface cracks.

[0110] The dislocation density of the indium phosphide single crystal is determined using the method described in GB / T20230-2022 "Indium Phosphide Single Crystal".

[0111] The content of sulfur and tin in indium phosphide single crystals was determined using the method specified in the following standard: "DB35 / T 1146-2011 Determination of impurity element content in silicon materials - Glow discharge mass spectrometry".

[0112] The carrier concentration was measured using a Hall instrument.

[0113] Preparation of sulfur- and tin-doped indium phosphide single crystal rods

[0114] In the following examples, a 4-inch diameter sulfur- and tin-doped indium phosphide single crystal rod is prepared. However, sulfur- and tin-doped indium phosphide single crystal rods of other diameters can also be prepared using the method of the present application.

[0115] The sulfur- and tin-doped indium phosphide single crystal rods were prepared according to the following steps.

[0116] 6 kg of indium phosphide polycrystals and a small amount of 6N high-purity red phosphorus were mixed with the amount of sulfur-containing dopant and tin-containing dopant as described in Table 1, and placed together with 0.2 kg of boron oxide sealant into a crucible with a seed crystal. The crucible was placed in a growth tube and vacuumed to less than 10 -3 The growth tube is sealed under a vacuum of 1.5 Pa. The growth tube is placed in a crystal growth furnace and heated using a multi-temperature zone system. The crucible is heated at a heating rate of 20°C / min, and the temperature is raised to 1100°C to melt the raw materials in the crucible and maintain for 4 hours; the melt in the crucible is cooled, and the temperature gradient of the melt is controlled to 2.5°C / cm and the cooling rate is controlled to 0.4°C / h, so that a sulfur- and tin-doped indium phosphide single crystal rod is crystallized and grown when the melt contacts the seed crystal. After the single crystal growth is completed, the sulfur- and tin-doped indium phosphide single crystal rod is cooled to room temperature. After cooling to room temperature, the single crystal rod is removed from the crucible to obtain a single crystal rod of InP single crystal with a diameter of 105 mm. In addition, a similar method and parameters are used, but the amount of raw materials is adjusted to prepare the indium phosphide single crystal rod in the comparative example.

[0117] The experimental data in Table 1 show that when sulfur or tin is doped alone, the yield is low, and the dislocation density is higher when tin is doped alone. However, when sulfur and tin are doped simultaneously, the dislocation density is significantly lower than that of crystals doped with tin alone, and is comparable to that of crystals doped with S alone. However, when sulfur and tin are doped simultaneously at the specified concentrations (sulfur: 0.5 ppm to 500 ppm, tin: 0.5 ppm to 1000 ppm), the yield of the crystals is significantly improved. In addition, the data from Comparative Example 4 show that when sulfur and tin are doped simultaneously, but the sulfur and / or tin content is not within the specified range (sulfur: 0.5 ppm to 500 ppm, tin: 0.5 ppm to 1000 ppm), the effect of improving the yield of the crystals is not significant. The data from Examples 1 to 4 show that when sulfur and tin are doped simultaneously, the yield improvement is most significant when the sulfur content in the indium phosphide crystals is greater than or equal to 10 ppm and less than or equal to 150 ppm, and the tin content in the indium phosphide crystals is greater than or equal to 2 ppm and less than or equal to 180 ppm.

[0118] Conclusion: Sulfur and tin co-doping has a lower dislocation density than single tin doping and a higher yield than single sulfur doping or single tin doping. When the indium phosphide crystal contains 0.5ppm to 500ppm of sulfur and 0.5ppm to 1000ppm of tin, the dislocation density can be reduced, twin defects can be reduced, and the yield of the indium phosphide crystal can be improved while ensuring the required carrier concentration range. In particular, when the sulfur content is within the required carrier concentration range and the tin content is within the range of 2 to 200ppm, the improvement in yield is particularly significant.

[0119] Preparation of sulfur- and tin-doped indium phosphide single crystals

[0120] The sulfur- and tin-doped indium phosphide single crystal rods prepared in the above embodiments were cut into sulfur- and tin-doped indium phosphide single crystal wafers according to the following steps.

[0121] Cutting: The sulfur- and tin-doped indium phosphide single crystal rod is cut into 800 μm thick initial single crystal wafers of sulfur- and tin-doped indium phosphide single crystal using a multi-wire saw. Figure 2 shows a schematic diagram of the single crystal rod fixture used in the preparation of the single crystal wafers of this application; a fixture comprising semi-enclosing graphite 9 is used to secure the sulfur- and tin-doped indium phosphide single crystal rod 8, facilitating its separation from the single crystal wafer in subsequent steps. During the cutting process, the semi-enclosing graphite is used to secure the circular sulfur- and tin-doped indium phosphide single crystal rod. After cutting, the initial single crystal wafers of sulfur- and tin-doped indium phosphide single crystal are manually removed, performed by the same person under the same conditions.

[0122] Chamfering: Use a chamfering machine to chamfer the edges of each circular single crystal wafer so that its edge cross-section becomes an arc.

[0123] Fixing: Place one side of the single crystal on a 5.2 cm diameter, 250 μm thick flat ceramic plate (Ra < 0.5 μm), and apply gentle pressure to ensure that there are no bubbles between the single crystal and the ceramic plate.

[0124] Surface treatment: The ceramic plate carrying the single crystal was placed in an etching solution at 35° C. for 12 seconds. The etching solution consisted of 1 mol % NH 3 , 10 mol % hydrogen peroxide, and the balance water.

[0125] Polishing: Then place the ceramic plate carrying the single crystal chip in the support pad cavity of the polishing machine (close to the ceramic plate) and fix it. First, use the rough polishing solution shown in Table 3 for the polishing equipment, and polish for 60 minutes under the rough polishing conditions shown in Table 2. After cleaning with deionized water (resistivity greater than 17.5 megohm·cm - based on the value at 25°C), dry it. Then use the fine polishing solution shown in Table 3 for 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 chip and place it on a heating furnace to melt the glue. Remove the single crystal chip from the ceramic plate, clean it with deionized water, and dry it.

[0126] Cleaning: a) At 10°C, immerse the single wafer in an aqueous solution containing 0.3 wt% NH3 and 1.3 wt% (unless otherwise stated, all solutions below are calculated by weight percentage based on the total weight of the solution) hydrogen peroxide for 5 minutes; b) At 10°C, rinse the surface of the single wafer with deionized water for 3 minutes; c) At 20°C, immerse the single wafer in a 10 wt% hydrogen peroxide solution for 5 minutes; d) At 15°C, rinse the surface of the single wafer with deionized water for 3 minutes; e) At 20°C, immerse the single wafer in a 10 wt% ammonia aqueous solution for 5 minutes; f) At 15°C, rinse the surface of the single wafer with deionized water for 3 minutes; g) Place the single wafer in a wafer spin dryer and dry it with hot nitrogen.

[0127] The thickness of the obtained indium phosphide single crystal wafer is 650 μm. The performance test results of the obtained indium phosphide single crystal wafers of various embodiments are shown in Table 4 below, where the carrier concentration is tested using a Hall instrument.

[0128] Table 2 Composition of rough polishing solution and polishing conditions

[0129] Table 3 Composition of fine polishing solution and polishing conditions

[0130] Table 4 Performance test results of InP single crystal

[0131] The data in Table 4 show that the InP single crystal wafers cut from the sulfur- and tin-doped indium phosphide single crystal rods prepared according to Examples 1 to 4 of the present application have the characteristics of high carrier density and low dislocation density, which meet the industrial application requirements of optoelectronic devices and electronic devices.

[0132] Although the above content has been described with reference to certain specific embodiments of the present application, it will be understood by those skilled in the art that changes may be made to the embodiments without departing from the principles and subject matter of the present application, and the scope of the present application is defined by the appended claims. All references mentioned above, including papers, patent documents, and standards, are incorporated herein by reference in their entirety.

Claims

1. An indium phosphide crystal, which is an N-type indium phosphide single crystal, wherein the indium phosphide crystal contains 0.5 ppm to 500 ppm of sulfur and 0.5 ppm to 1000 ppm of tin. 2 . The indium phosphide crystal according to claim 1 , wherein the sulfur content is 0.5 ppm to 500 ppm, preferably 0.8 ppm to 400 ppm, and more preferably 1 ppm to 300 ppm. 3 . The indium phosphide crystal according to claim 1 , wherein the tin content is 0.5 ppm to 1000 ppm, preferably 1 ppm to 500 ppm, and more preferably 2 ppm to 300 ppm.

4. The indium phosphide crystal according to claims 1 to 3, wherein the carrier concentration of the indium phosphide crystal is 1×10 17 cm -3 to 5×10 19 cm -3 , for example 1×10 18 cm -3 to 1×10 19 cm -3 , preferably 1×10 18 cm -3 to 8×10 18 cm -3 , or for example 1×10 17 cm -3 to 9×10 17 cm -3 , preferably 3×10 17 cm -3 to 5×10 17 cm -3 . 5 . The indium phosphide crystal according to claim 1 , wherein the indium phosphide crystal is in the form of an indium phosphide single crystal rod or a single crystal wafer.

6. A method for preparing an N-type indium phosphide single crystal, the method comprising the steps of placing phosphorus, an indium phosphide polycrystal, a dopant containing sulfur, a dopant containing tin, or a dopant containing sulfur and tin, together with a sealant, into a growth container, such as a crucible, provided with a seed crystal; and placing the container into a crystal growth furnace and heating the container to a temperature above the melting point of indium phosphide.

7. The method according to claim 6, further comprising the step of gradually cooling the melt in the container to obtain the N-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 rod growth zone to increase and maintain the temperature above the melting point of indium phosphide.

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

10. The method according to any one of claims 6 to 9, wherein The dopant containing sulfur is selected from sulfur, indium sulfide, or a mixture thereof; The dopant containing tin is selected from tin, tin phosphide, alloy of tin and indium, or a mixture thereof.

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

12. Use of a combination of a sulfur-containing dopant and a tin-containing dopant, or a dopant containing sulfur and tin, in an indium phosphide crystal preparation process for increasing carrier concentration while reducing dislocation density, reducing twin defects, and / or improving the yield of indium phosphide crystals.

13. An electronic device or optoelectronic device, which is made of the indium phosphide crystal according to any one of claims 1 to 5 or contains a component made of the indium phosphide crystal according to any one of claims 1 to 5. The optoelectronic device according to claim 13 , which is selected from a laser, a detector, or a light emitting diode. The electronic device according to claim 13 , which is selected from HBT, MESFET, or PHEMT.

Images