Indium phosphide crystal containing zinc and iron, single crystal wafer, preparation method of indium phosphide crystal and single crystal wafer, and device

Abstract

The invention relates to an indium phosphide crystal doped with zinc and iron, a single crystal wafer, a preparation method of the indium phosphide crystal and the single crystal wafer and a device. Specifically, the invention relates to an indium phosphide crystal which is a P-type indium phosphide crystal, and the indium phosphide crystal contains 0.5 ppm to 500 ppm of a zinc element and further contains 0.02 ppm to 50 ppm of an iron element. The invention also relates to a method for preparing the indium phosphide crystal doped with zinc and iron and a device prepared by using the indium phosphide crystal. The zinc and iron doped indium phosphide crystal obtained according to the invention has the advantages of low dislocation density, few defects and high yield.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor processing and manufacturing, and in particular to indium phosphide crystals and methods for preparing the same; further to indium phosphide single wafers made of the indium phosphide crystals and methods for preparing the same, and devices comprising the indium phosphide crystals. BACKGROUND

[0002] Indium phosphide (InP) is a III-V compound semiconductor material, which has higher electron mobility than silicon or gallium arsenide, and also has higher photoelectric conversion efficiency, stronger radiation resistance, and high thermal conductivity, etc. These excellent properties make it widely used in integrated circuits, high-speed high-frequency devices, optoelectronic devices, optical fiber communication, and other fields.

[0003] The manufacturing of InP single wafers generally includes the steps of growing single crystals, cutting out coarse wafers from single crystal rods, edge grinding of the coarse wafers, grinding, rough polishing, fine polishing, cleaning, drying, etc. Due to the very high dissociation pressure of InP near its melting point temperature (about 1335±7K) (about 2.75MPa), its critical resolved shear stress (CRSS) and interlayer stacking fault energy are relatively low, which leads to the formation of twinning defects and high dislocation density when growing intrinsic indium phosphide single crystals, usually reaching several hundred, several thousand, or even tens of thousands. To meet the application requirements, certain impurities are intentionally introduced during the growth of indium phosphide single crystals to change its electronic structure and conductivity properties. By introducing different impurities, P-type or N-type indium phosphide single crystals can be formed. However, during the growth of the above two types of indium phosphide single crystals (i.e. P-type InP single crystals and N-type InP single crystals), the problem of low stacking fault energy of indium phosphide crystals, the formation of twinning defects, low carrier concentration, and low yield rate cannot be avoided. SUMMARY

[0004] Therefore, there is a need in the art for an InP crystal with low dislocation density, no twinning defects, and good conductivity performance and high yield rate.

[0005] To solve the above problems, the present application proposes to simultaneously introduce two or more doping elements into the indium phosphide crystal growth melt to obtain an indium phosphide single crystal with low dislocation density, few twinning defects, and high carrier concentration, thereby improving the yield rate of the indium phosphide single crystal.

[0006] Specifically, the first aspect of the present application provides an indium phosphide crystal, which is a P-type indium phosphide single crystal, containing 0.5ppm to 500ppm of zinc element (Zn), and further containing 0.02ppm to 50ppm of iron element (Fe).

[0007] In another aspect of the present application, a method for preparing an indium phosphide crystal is provided, which comprises the steps of: loading phosphorus, indium phosphide polycrystal, a dopant containing an iron element and a dopant containing a zinc element (or a dopant containing zinc and iron), together with a sealant, into a growth container (for example, a crucible) provided with a seed crystal; and placing the container into a crystal growth furnace and heating to a temperature above the melting point of indium phosphide; preferably, the content of the zinc element in the obtained indium phosphide crystal is 0.5 ppm to 500 ppm, and the content of the iron element is 0.02 ppm to 50 ppm.

[0008] In yet another aspect of the present application, an indium phosphide single wafer is provided, which is made of the indium phosphide crystal according to the above or made of the indium phosphide crystal obtained according to the above method.

[0009] In yet another aspect of the present application, an electronic or optoelectronic device is provided, which is made of the above indium phosphide single wafer or contains a component made of the above indium phosphide single wafer.

[0010] In yet another aspect of the present application, the combination of the dopant containing an iron element and the dopant containing a zinc element or the dopant containing zinc and iron is used in the preparation of the indium phosphide crystal to reduce the dislocation density, reduce the formation of twin defects, and / or improve the yield of the indium phosphide crystal while increasing the carrier concentration.

[0011] The indium phosphide crystal doped with zinc and iron obtained according to the present application is a P-type indium phosphide single crystal, which has a low dislocation density and reduces the formation of twins, so that the yield of the indium phosphide crystal is high and a single wafer with uniform and stable performance can be obtained, and the obtained P-type indium phosphide crystal has good electrical conductivity, so that it can be applied to optoelectronic devices such as lasers and photodetectors, electronic devices such as transistors, and high-frequency components. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a sectional view of an embodiment of a crystal growth apparatus comprising a sealed container for growing an indium phosphide single crystal doped with zinc and incorporating iron.

[0013] Figure 2 is a schematic view of a single crystal rod fixing device used in the preparation of a single wafer according to the present application. DETAILED DESCRIPTION

[0014] In order to make the application purposes, technical solutions and beneficial technical effects of the present application clearer, the present application will be described in detail below in combination with specific embodiments. It should be understood that the embodiments described in the present specification are only for the purpose of explaining the present application, and are not intended to limit the present application.

[0015] For simplicity, only some numerical ranges are explicitly recited herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with any other lower limit to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. Furthermore, although a range is recited, it is to be understood that every point or individual number within the range is also specifically disclosed. Thus, every point or individual number can be combined with every other point or individual number to form a new range not explicitly recited.

[0016] If not particularly specified, all the 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.

[0017] If not particularly specified, all the technical features and optional technical features or preferred technical features 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.

[0018] As described above, the present application provides a phosphorus indium crystal which is a P-type phosphorus indium single crystal, the phosphorus indium crystal containing 0.5 ppm to 500 ppm of zinc element and further containing 0.02 ppm to 50 ppm of iron element.

[0019] In the prior art, a single element is generally used to form a P-type phosphorus indium crystal, and there is no report on a phosphorus indium crystal doped with both iron and zinc. Even if the prior art occasionally involves a phosphorus indium crystal containing both iron and zinc elements, one of the elements is the main element, and the other element exists as a trace impurity element, and the content ratio of the two is greatly different (more than one million times).

[0020] Without being bound by any theory, the applicant has found that:

[0021] (1) In actual crystal growth, the zinc element has a significant impurity hardening effect in InP, and the addition of a certain amount of zinc element can effectively strengthen the lattice strength of InP crystal, thereby greatly reducing the point defect density of InP crystal. However, InP doped with zinc element is prone to twinning in the process of crystal growth, which causes the problem of low single crystal rate. This is also one of the reasons for the high cost of InP single crystal. In particular, in recent years, the market requires higher and higher carrier concentration of P-type InP crystal, which requires more zinc element-containing dopants to be added during the growth of InP crystal. However, the addition of zinc element alone will greatly increase the probability of twinning in the process of InP crystal growth, greatly reducing the single crystal rate of the crystal.

[0022] (2) In the actual production process, it is found that the addition of iron element as a dopant can inhibit the generation of twin crystals to a certain extent. The inventors believe that this may be due to the low segregation coefficient of iron in indium phosphide, which improves the viscosity of the melt during InP crystal growth, which is beneficial to the stability of the InP hot melt, can effectively change the solid-liquid interface conditions, inhibit the growth of InP single crystal in other crystal directions, and thus effectively inhibit the generation of twin crystals. However, iron has little effect on strengthening the lattice, so that the point defect density of iron-doped InP crystal is relatively high, which can reach several hundred or even thousands (cm -2 ) According to the article "A systematic study of the electrical properties of Fe-doped InP single crystal" (Journal of Materials Science, Vol 16, 554-557, 1981) published by B. COCKAYNE et al., it is recorded that the segregation coefficient of iron in InP crystal is 1.6E-3.

[0023] (3) The present application will zinc and iron as a certain proportion of dopant, together into the indium phosphide crystal, which can reduce the dislocation density of the crystal, and can inhibit the generation of twin crystals to a certain extent, that is, there is a certain degree of synergistic effect, thereby effectively improving the single crystal yield (yield); And by adjusting the doping ratio, the application requirements of low dislocation density and high carrier concentration can be fully met.

[0024] In this paper, "segregation coefficient", also known as effective distribution coefficient, refers to the solubility of impurities in different phases at the interface between solid and liquid phases, so the concentration of impurities in the materials on both sides of the interface is different. The segregation coefficient is represented by K, K = (solubility of impurities in solid phase) / (solubility of impurities in liquid phase) (K = Cs / Cl). The segregation coefficient of each element can be determined by those skilled in the art by known methods in the art, for example, the segregation coefficient of the element can be determined according to the method described in the article "Growth and Properties of Low Dislocation Iron-doped Phosphorus Single Crystal" (Journal of Applied Sciences, Vol. 1, No. 3, July 1983) published by Fang Dunfu et al.

[0025] In some embodiments of the present application, the content of zinc element in the indium phosphide crystal can be 0.5 ppm to 500 ppm; for example, the doping amount of the zinc element 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, or within any content range formed by taking any of the above contents or any content disclosed in the embodiments of the present application as the end value. As an example, the content of zinc element in the indium phosphide crystal can be 0.8 ppm to 500 ppm, preferably 1 ppm to 400 ppm, and more preferably 1.2 ppm to 300 ppm. In some preferred embodiments of the present application, the content of zinc element in the indium phosphide crystal can be 5 ppm to 450 ppm, preferably 10 ppm to 400 ppm, more preferably 20 ppm to 300 ppm, and even more preferably 25 ppm to 200 ppm.

[0026] In some embodiments of the present application, the content of iron element in the indium phosphide crystal can be 0.02 ppm to 50 ppm; for example, the doping amount of the iron element can be 0.020 ppm, 0.030 ppm, 0.040 ppm, 0.060 ppm, 0.070 ppm, 0.080 ppm, 0.1 ppm, 0.2 ppm, 0.3 ppm, 0.4 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, or within any content range formed by taking any of the above contents or any content disclosed in the embodiments of the present application as the end value. As an example, the content of iron element in the indium phosphide crystal can be 0.03 ppm to 40 ppm, preferably 0.03 ppm to 20 ppm, and more preferably 0.03 ppm to 10 ppm. In some preferred embodiments of the present application, the content of iron element in the indium phosphide crystal can be 0.02 ppm to 45 ppm, preferably 0.025 ppm to 35 ppm, more preferably 0.03 ppm to 25 ppm, and even more preferably 0.03 ppm to 15 ppm.

[0027] In some embodiments of the present application, in addition to the iron element and the zinc element, the indium phosphide crystal can also contain other elements added or doped for other purposes, such as magnesium (Mg) and the like. In some preferred embodiments of the present application, the other elements can be selected from elements with low coagulation coefficients and do not affect the main performance of the original P-type indium phosphide crystal and the use of single crystal wafers for epitaxy.

[0028] It should be noted that the indium phosphide crystal provided in the present application is usually in the form of a single crystal rod. As for the indium phosphide crystal in the form of a single crystal rod, it has been found that the content of the doping element (positively proportional to the carrier concentration CC) at different cross sections along the growth direction of the single crystal rod is different, which is mainly related to the segregation coefficient K of the doping element (impurity element) in indium phosphide.

[0029] The distribution relationship of the location of the doping element content in the crystal rod is given in the following formula (according to Pfann, W. G., “Zone Melting”),

[0030] Cx= K·Co(1-X)(K-1)

[0031] wherein 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; Co is the solubility of the doping element in the liquid phase in the molten state before crystallization.

[0032] That is, the distribution of the doping zinc and iron elements (K < 1) in the indium phosphide crystal is not uniform; the content thereof gradually increases in a non-linear manner from the head of the crystal rod where the growth starts to the tail of the crystal. Therefore, in the case where the indium phosphide crystal is in the form of a single crystal rod or in other cases where the distribution of the doping element in the indium phosphide crystal is not uniform, the range specified in the present application for the content of the doping element in the indium phosphide crystal should be understood as the content of the doping element at any position of the finished single crystal rod (but the most head and tail parts of the single crystal rod which should be discarded during processing should be excluded).

[0033] The indium phosphide crystal provided in the present application can also be in the form of a single crystal wafer. The single crystal wafer can be obtained, for example, by cutting the indium phosphide single crystal rod. When the indium phosphide crystal is in the form of a single crystal wafer, the type of the doping element and the content of the doping element in the crystal are also the same as described above.

[0034] The indium phosphide crystal of the present application is a P-type indium phosphide single crystal. In some preferred embodiments of the present application, the carrier concentration of the indium phosphide single crystal is 1 x 10 17 cm- 3 to 5 x 10 19 cm- 3 , for example, 1 x 10 18 cm -3 to 1 x 10 19 cm -3 , preferably 1 x 10 18 cm -3 to 8 x 10 18 cm -3 , or 8 x 10 17 cm -3 to 9 x 1018 cm -3 , preferably 9x10 17 cm -3 to 8x10 18 cm -3 .

[0035] Herein, the carrier concentration means the number of carriers per unit volume (cm 3 ). It is equal to the concentration of ionized impurities in the absence of compensation at room temperature. The determination of the carrier concentration can be performed using methods known in the art, for example with a Hall meter.

[0036] The indium phosphide single crystal of the present application has low dislocation and uniform dislocation distribution. In some preferred embodiments of the present application, the average dislocation density of the indium phosphide crystal can be 800 / cm 2 or below, or 500 / cm 2 or below, or 100 / cm 2 or below, or even 80 / cm 2 or below. Particularly preferably, the average dislocation density of the indium phosphide crystal can reach 50 / cm 2 or lower.

[0037] In the present application, the dislocation density of the zinc- and iron-doped indium phosphide single crystal is determined by the method described in GB / T 20230-2022 “Indium Phosphide Single Crystal”.

[0038] In yet another aspect, the present application provides a method for preparing an indium phosphide crystal, which comprises the steps of: loading phosphorus, indium phosphide polycrystal, a dopant containing iron element and a dopant containing zinc element or a dopant containing iron and zinc elements, together with a sealing agent, into a growth container (e.g. a crucible) provided with a seed crystal; and placing the container into a crystal growth furnace and heating to a temperature above the melting point of indium phosphide.

[0039] Preferably, the content of the zinc element in the indium phosphide crystal is 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 content of the iron element in the indium phosphide crystal is 0.020 ppm to 50 ppm, for example, 0.020 ppm, 0.030 ppm, 0.040 ppm, 0.060 ppm, 0.070 ppm, 0.080 ppm, 0.1 ppm, 0.2 ppm, 0.3 ppm, 0.4 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, etc., or in any content range formed by taking any of the above relative amounts or any relative amount disclosed in the embodiments of the present application as an end value.

[0040] In the present application, the content of the iron element and the zinc element in the indium phosphide crystal is measured by glow discharge mass spectrometry (GDMS). In the glow discharge ion source, a potential difference is applied between the cathode (the 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 particles formed in the plasma are attracted to the sample surface, and their impact causes the surface to sputter and produce neutral particles. These neutral particles diffuse into the plasma, where they are subsequently ionized in the plasma potential region, and can then be extracted into the mass spectrometer for quantitative analysis. Reference can be made to the current detection standard, "DB35 / T 1146-2011 Determination of Impurity Element Content in Silicon Materials by Glow Discharge Mass Spectrometry".

[0041] In the present application, as the raw material in the preparation method of the indium phosphide crystal, the dopant containing the doped element is selected from the element itself, the phosphide of the element, the alloy of the element and indium, or a mixture of the above substances. Herein, the term "dopant" is used to refer to a substance used to provide elements such as iron or zinc in the preparation process of the indium phosphide crystal; iron or zinc can be used, and iron- or zinc-containing compounds suitable for industrial production environment can also be used. The dopant used is preferably of high purity, preferably a purity of 99.00% or higher, for example, 99.99% or higher.

[0042] For example, in some preferred embodiments of the present application, the dopant containing iron element is iron, a phosphide of iron (e.g., Fe2P or Fe3P), an alloy of iron and indium, or any mixture thereof. For example, in some preferred embodiments of the present application, the dopant containing zinc element is selected from zinc, a phosphide of zinc, an alloy of zinc and indium, or a mixture of the above. In addition, zinc and iron can also be present in the same dopant, in which case the dopant is both a zinc-containing dopant and an iron-containing dopant.

[0043] In the present application, the apparatuses (e.g., growth container, furnace, etc.) used in the method for preparing indium phosphide crystal can use conventional apparatuses for preparing N-type indium phosphide single crystal or P-type indium phosphide single crystal that are known or commonly used in the art.

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

[0045] In the present application, the operation of loading phosphorus, indium phosphide polycrystal, iron-containing dopant, zinc-containing dopant, or dopant containing zinc and iron, and sealing agent into the growth container can be implemented in various ways. For example, the phosphorus, indium phosphide polycrystal, iron-containing dopant, zinc-containing dopant, or dopant containing zinc and iron, and sealing agent can be added into the growth container simultaneously or sequentially, or the iron-containing dopant and / or zinc-containing dopant or dopant containing zinc and iron can be pre-mixed into the indium phosphide polycrystal

[0046] (or the dopant is introduced when preparing the indium phosphide polycrystal to form the indium phosphide polycrystal containing the doping element) and then added into the growth container, etc. All these implementation ways can be used to prepare the indium phosphide crystal of the present application. On this basis, the person skilled in the art can also conceive other equivalent implementation ways, and all the above implementation ways and other equivalent implementation ways are considered to be within the disclosure scope of the present application.

[0047] In some preferred embodiments of the present application, the amount of the iron-containing dopant, zinc-containing dopant, or dopant containing zinc and iron is such that the content of the zinc element in the indium phosphide crystal is 0.5 ppm to 500 ppm, and the content of the iron element in the indium phosphide crystal is 0.020 ppm to 50 ppm, more preferably such that the carrier concentration of the obtained indium phosphide single crystal rod is 1 x 1010cm-3to 5 x 1010cm-3in the effective length, preferably 1 x 1011cm-3to 5 x 1011cm-3, and more preferably 1 x 1012cm-3to 5 x 1012cm-3. 17 cm -3 to 5 x 1010cm 19 cm -3 , preferably 1 x 1011cm 18 cm -3to 1 x 10 19 cm -3 .

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

[0049] a 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 into a crystal growth furnace and heating to a temperature above the melting point of indium phosphide comprises: placing the container into a crystal growth furnace, heating 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, increasing the temperature and maintaining it above the melting point of indium phosphide; and then gradually cooling the melt in the resulting container to obtain P-type indium phosphide single crystals.

[0051] The amounts of raw materials phosphorus, indium phosphide polycrystal, dopant and sealing agent used in the method for preparing indium phosphide crystals of the present application can be determined by those skilled in the art according to actual needs.

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

[0053] In some preferred embodiments of the present application, the method for preparing crystals is selected from the vertical gradient freezing method (VGF), in which the crucible can be moved in a temperature field or the crucible is kept stationary while the temperature field is changed.

[0054] In some preferred embodiments of the present application, the vertical gradient freezing method (VGF) is used, and the steps thereof comprise:

[0055] 1) loading phosphorus, indium phosphide polycrystal, a dopant containing iron element and a dopant containing zinc element or a dopant containing zinc and iron, together with a sealing agent boron oxide, into a crucible provided with a seed crystal;

[0056] 2) placing the crucible of step 1) into a growth tube (preferably a quartz tube, but other types of growth tubes can also be used), and sealing the growth tube under vacuum;

[0057] 3) placing the growth tube of step 2) with the crucible sealed therein 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 rod growth zone), increasing the temperature and maintaining it above the melting point of indium phosphide;

[0058] 4) gradually cooling the melt in the crucible obtained in step 3) to obtain P-type indium phosphide single crystals containing zinc and iron.

[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 iron-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 iron 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] like Figure 1 As shown, 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 iron-containing and zinc-containing dopants, or dopants containing both zinc and iron. 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 iron. The amount of sealant used is the conventional amount used in the art.

[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 iron / zinc dual-doped P-type indium phosphide single crystals.

[0063] Another aspect of this application provides the use of a combination of iron-containing dopants and zinc-containing dopants, or a dopant containing both zinc and iron, 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 resulting indium phosphide crystal is from 0.5 ppm to 500 ppm, and the iron content is from 0.020 ppm to 50 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 iron-doped indium phosphide single-crystal rods of this application can be cut to produce zinc- and iron-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 the present application, the diameter of a single crystal wafer shall be understood as follows: in the case of a circular single crystal wafer, the diameter of the circle; in the case of a single crystal wafer having another shape (e.g. an irregular circle, a square, a rectangle, etc.), the diameter of the circle that is drawn with the center of the single crystal wafer as the center of the circle and that includes all parts of the single crystal wafer.

[0066] In the present application, the term "effective length" means the actual length of a single crystal ingot that can be used to cut a single crystal wafer.

[0067] The zinc- and iron-doped indium phosphide single crystal wafers according to the present application have a thickness of 200 to 2000 pm, preferably 300 to 1200 pm.

[0068] The zinc- and iron-doped indium phosphide single crystal wafers according to the present application are cut from zinc- and iron-doped indium phosphide single crystal ingots, which are single crystal ingots having a circular cross-section (referred to as circular single crystal ingots) and typically have a diameter of the circular cross-section of not more than 12 inches, preferably 1 to 8 inches. Of course, the zinc- and iron-doped indium phosphide single crystal ingots can also be single crystal ingots having another shape of the cross-section, for example, a square (a square or a rectangle) cross-section obtained by processing a circular single crystal ingot, in which case the cut wafers are non-circular zinc- and iron-doped indium phosphide single crystal wafers.

[0069] The zinc- and iron-doped indium phosphide single crystal wafers according to the present application are preferably cut from single crystal ingots prepared by the methods described herein. The zinc- and iron-doped indium phosphide single crystal wafers according to the present application can be processed in the same way as conventional iron-doped single crystal wafers. Specific examples of processing methods for the zinc- and iron-doped indium phosphide single crystal wafers according to the present application can be found in Chinese patent CN 116043318 A, the content of which is incorporated herein by reference.

[0070] The zinc- and iron-doped indium phosphide single crystal wafers described herein can be used for epitaxial growth thereon or further processed to 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] In a further aspect, the present application provides an electronic or optoelectronic device made of or containing a component made of the zinc- and iron-doped indium phosphide single crystal wafer described above. The optoelectronic device includes, for example, lasers, detectors, light emitting diodes, etc., and the electronic device includes, for example, HBTs, MESFETs, PHEMTs, etc.

[0072] The present application can be illustrated by the following embodiments:

[0073] 1. An indium phosphide crystal which is a P-type indium phosphide single crystal, the indium phosphide crystal containing 0.5 ppm to 500 ppm of a zinc element, and further containing 0.020 ppm to 50 ppm of an iron element.

[0074] 2. The indium phosphide crystal according to Embodiment 1, wherein the content of the zinc element 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 content of the iron element is 0.030 ppm to 40 ppm, preferably 0.03 ppm to 20 ppm, more preferably 0.03 ppm to 10 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 x 1010 cm"3 to 5 x 1010 cm"3, for example, 1 x 1010 cm"3 to 1 x 1011 cm"3, preferably 1 x 1010 cm"3 to 8 x 1010 cm"3, or for example, 8 x 1010 cm"3 to 9 x 1010 cm"3, preferably 9 x 1010 cm"3 to 8 x 1011 cm"3. 17 cm -3 19 cm -3 18 cm -3 19 cm -3 18 cm -3 18 cm -3 17 cm -3 18 cm -3 17 cm -3 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 ingot.

[0078] 6. A method of producing an indium phosphide crystal, wherein the indium phosphide crystal is a P-type indium phosphide single crystal, the method comprising the steps of: charging a growth container, such as a crucible, provided with a seed crystal, with phosphorus, an indium phosphide polycrystal, a dopant containing an iron element, and a dopant containing a zinc element or a dopant containing zinc and iron, together with a sealing agent; and

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

[0080] ​​​​​​​​​7. The method according to embodiment 6, further comprising 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 into a crystal growth furnace and heating to a temperature above the melting point of indium phosphide comprises placing the container into a crystal growth furnace and heating 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, increasing the temperature and maintaining 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 resulting indium phosphide crystal is 0.5 ppm to 500 ppm and the content of iron in the resulting indium phosphide crystal is 0.020 ppm to 50 ppm.

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

[0084] the iron containing dopant is selected from iron, a phosphide of iron, an alloy of iron and indium, or any mixture thereof;

[0085] the zinc containing dopant is selected from zinc, a phosphide of zinc, an alloy of zinc and indium, or a mixture of the above.

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

[0087] 12. Use of a combination of an iron containing dopant and a zinc containing dopant or a dopant containing both zinc and iron in the production of an indium phosphide crystal for increasing the carrier concentration while reducing the dislocation density, reducing the twin defect density, and / or increasing the yield of the indium phosphide crystal.

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

[0089] 14. The indium phosphide single crystal wafer according to embodiment 13, wherein the single crystal wafer is used for epitaxial growth thereon or is further processed into a device, the device comprising 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.

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

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

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

[0093] The indium phosphide crystal containing zinc and iron obtained by the present application has less twinning and low defect density, high yield, can greatly reduce the cost, and has good electrical properties, so that it can be more widely used in optoelectronic devices such as lasers and photodetectors, and high-frequency electronic devices, etc.

[0094] Embodiments

[0095] In order to better understand the present application, the present application will be described in detail below in conjunction with the embodiments and drawings, but it should be recognized that these embodiments are only illustrative of the present application, and are not intended to limit the present 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 are synthesized according to conventional methods and used directly without further purification, and the instruments used in the examples are commercially available.

[0097] Production apparatus

[0098] Figure 1A cross-sectional view showing one example of a crystal growth apparatus containing a sealed container for the growth of doped zinc and iron indium phosphide single crystals. The apparatus is disposed within a high pressure chamber 1 and can include a growth tube 3 located in a furnace, wherein the heater 2 is comprised of multiple temperature zones, each temperature zone being individually controlled by a computer controlled by a control system. The pressure within the high pressure chamber 1 is regulated to, for example, about 2 to 4 MPa. The temperature of each temperature zone is regulated to provide the temperature distribution and temperature gradient required to control the solidification of the melt, and the temperature distribution and temperature gradient in the furnace is adjusted so that the crystallization interface moves upward as desired through the melt, for example, a temperature gradient of 0.1 to 10 °C / cm is established in the single crystal rod growth zone, and a lower temperature gradient is established at the seed end. The crucible 4 in the growth tube (quartz tube) 3 has a seed slot for holding a seed crystal 7 along the top of which a single crystal is grown. In one embodiment, the crucible 4 can be a pyrolytic boron nitride structure having a cylindrical crystal growth portion, a smaller diameter seed slot cylinder, and a conical 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 one exemplary embodiment, the seed slot cylinder at the bottom of the crucible 4 can have a closed bottom and a diameter slightly larger than the seed crystal 7. The cylindrical crystal growth portion and the seed slot cylinder can have straight walls, or taper outwardly at about 1 to 30 degrees to facilitate removal of the crystal from the crucible 4.

[0099] The crucible 4 fits within the interior of the growth tube 3 and has a narrow gap therebetween. The growth tube 3 is closed at the bottom in the region of the seed slot and is sealed at the top after the crucible and feedstock are loaded.

[0100] Because the growth tube-crucible assembly has a funnel shape, a growth tube support is required to accommodate the funnel shape and to hold 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 according to the different shapes.

[0101] In the VGF crystal growth method, the crystallization temperature gradient of the stationary heat source is moved electrically, while the crystal is stationary.

[0102] To implement the vertical gradient freeze growth, the desired temperature gradient distribution is established in the furnace, and the power to the heating zones of the furnace is individually and separately controlled by a computer programmed to heat and cool to accommodate the crystallization temperature and temperature gradient requirements of the furnace. For the production of single crystal rods, for example, the temperature fluctuations of the furnace can need to be controlled to < ± 1 °C. During furnace preparation, the polycrystalline feedstock 6 of phosphorus, indium phosphide containing dopants, is loaded into the growth tube 3.

[0103] In an embodiment, elemental iron and elemental zinc are used as dopants. A (100) oriented seed crystal is loaded into a crucible seed slot, and then the charge is loaded. The charge (containing the appropriate amount of dopants) is loaded into a crucible, and the crucible is placed into a growth tube 3. The growth tube with the crucible is connected to a vacuum system and evacuated, and then the growth tube is sealed. The sealed growth tube is then loaded into a furnace, as shown in FIG. 1. The furnace is turned on, and the growth tube and its contents are heated to a temperature above the melting point of indium phosphide, 1050 °C. The temperature gradient at the crystallization interface can be adjusted to be between 0.1 and 10 °C / cm, depending on the location in the single crystal ingot. The entire temperature profile is adjusted to give a crystallization rate of 2 to 5 mm / h. Figure 1

[0104] The indium phosphide single crystal ingot doped with zinc and iron grown using the exemplary growth parameters described above can be used to cut wafers.

[0105] The growth procedure is designed to give the appropriate growth rate and temperature gradient near the solid-liquid interface from the seed end to the end of the single crystal growth (or the entire melt solidification growth into a solid single crystal).

[0106] Under this growth procedure and with the appropriate amount of dopants, single crystal growth is maintained throughout the length of the single crystal ingot. For example, indium phosphide single crystal ingots doped with zinc and iron having a diameter of 2 to 6 inches can be grown.

[0107] After all of the charge in the crucible has solidified, the grown single crystal ingot is cooled to room temperature under temperature control.

[0108] Performance test

[0109] The appearance quality of the prepared indium phosphide single crystal ingot doped with zinc and iron is detected by visual inspection under a daylight lamp.

[0110] The detection conditions for the initial wafers of the prepared indium phosphide single crystal ingot doped with zinc and iron are as follows: the single crystal wafers are intact and the surface is free of cracks.

[0111] The dislocation density of the indium phosphide single crystal is determined using the method described in GB / T 20230-2022 “Indium Phosphide Single Crystal”.

[0112] The content of zinc and iron in the indium phosphide single crystal is determined using the method specified in the standard “DB35 / T 1146-2011 Determination of Impurity Element Content in Silicon Materials by Glow Discharge Mass Spectrometry”.

[0113] The carrier concentration is tested using a Hall instrument.

[0114] Preparation of zinc- and iron-doped indium phosphide single crystal rods

[0115] ​In the following examples, zinc and iron doped indium phosphide single crystal rods of 4 inch diameter were prepared, however, zinc and iron doped indium phosphide single crystal rods of other diameter sizes can also be prepared using the method of the present application.

[0116] Zinc and iron doped indium phosphide single crystal rods were prepared according to the following procedure.

[0117] Six kilograms of indium phosphide polycrystalline and a small amount of 6N high purity red phosphorus were mixed with the amounts of iron containing dopant and zinc containing dopant as described in Table 1, together with 0.2 kg of boron oxide sealant, and loaded into a crucible provided with a seed crystal. The crucible was placed in a growth tube, and the growth tube was sealed under vacuum of less than 10 -3 Pa. The growth tube was placed in a crystal growth furnace, and the crucible was heated using a multi-zone system at a heating rate of 20 °C / min to raise the temperature to 1100 °C to melt the raw materials in the crucible and maintain for 4 h. The resulting melt in the crucible was cooled while controlling the temperature gradient of the melt to be 2.5 °C / cm and the cooling rate to be 0.4 °C / h to allow the melt to contact the seed crystal to grow a zinc and iron doped indium phosphide single crystal rod. After the single crystal growth was completed, the zinc and iron doped indium phosphide single crystal rod was cooled to room temperature. After cooling to room temperature, the single crystal rod was taken out of the crucible to obtain an InP single crystal rod of 105 mm in diameter. In addition, indium phosphide single crystal rods in Comparative Examples were prepared using similar methods and parameters, but adjusting the amount of raw materials.

[0118]

[0119] From the experimental data in Table 1, it can be seen that when zinc is doped alone, the yield is low; when iron is doped alone, the dislocation density is high and the crystal exhibits semi-insulating properties, but the yield is high; and when zinc and iron are doped simultaneously, the dislocation density is significantly lower than that of the crystal doped with iron alone, and is on par with that of the crystal doped with zinc alone, but the yield of the crystal is greatly improved when zinc and iron are doped simultaneously at the specified contents (zinc: 0.5 ppm to 500 ppm, iron: 0.02 ppm to 50 ppm). In addition, the data of Comparative Example 4 shows that when zinc and iron are doped simultaneously, but the contents of iron and / or zinc are not within the specified range (zinc: 0.5 ppm to 500 ppm, iron: 0.03 ppm to 30 ppm), the effect of improving the yield of the crystal is not obvious; the data of Examples 1 to 4 shows that when zinc and iron are doped simultaneously, the improvement of the yield of the crystal is most significant when the content of zinc in the indium phosphide crystal is greater than or equal to 10 ppm and less than or equal to 150 ppm, and the content of iron in the indium phosphide crystal is greater than or equal to 0.03 ppm and less than or equal to 20 ppm.

[0120] Conclusion: The double doping of zinc and iron in the ranges of 0.5 ppm to 500 ppm of zinc and 0.02 ppm to 50 ppm of iron or the more preferred ranges of iron and zinc above results in a lower dislocation density, a higher carrier concentration, and a higher yield than the single doping of iron. When the indium phosphide crystal contains 0.5 ppm to 500 ppm of zinc and 0.020 ppm to 50 ppm of iron, the dislocation density, the twin defect, and the yield of the indium phosphide crystal can be reduced while maintaining the required carrier concentration range. The improvement in yield is particularly significant when the content of zinc is in the required carrier concentration range and the content of iron is in the range of 0.03 ppm to 20 ppm.

[0121] Preparation of zinc- and iron-doped indium phosphide single crystal wafers

[0122] The zinc and iron doped indium phosphide single crystal rods prepared in the above examples were cut into zinc and iron doped indium phosphide single crystal wafers according to the following steps.

[0123] Cutting: The zinc and iron doped indium phosphide single crystal rods were cut into zinc and iron doped indium phosphide single crystal initial wafers with a thickness of 800 μm using a multi-wire saw. Figure 2 A schematic diagram of a single crystal rod fixing device used in the preparation of the single crystal wafers of the present application is shown; wherein the zinc and iron doped indium phosphide single crystal rod 8 is fixed by the fixing device using semi-enclosed graphite 9 to facilitate its separation from the single crystal wafer in subsequent steps. During the cutting process, the semi-enclosed graphite is used to fix the circular zinc and iron doped indium phosphide single crystal rod. After cutting, the zinc and iron doped indium phosphide single crystal initial wafer is manually removed, and the operation is completed by the same person under the same conditions.

[0124] Chamfering: The edge chamfering process was performed on each piece of circular single crystal wafer using a chamfering machine to make the edge cross-section arc-shaped.

[0125] Fixing: One side of the single crystal wafer was placed on a 5.2 cm diameter circular flat ceramic plate (Ra < 0.5 microns) with a thickness of 250 μm, and a light pressure was applied to ensure that there were no air bubbles between the single crystal wafer and the ceramic plate.

[0126] Surface treatment: The ceramic plate carrying the single crystal wafer was placed in an etching solution at 35°C for 12 seconds, and the composition of the etching solution was 1 mole % NH3, 10 mole % hydrogen peroxide, and the balance being water.

[0127] Polishing: The ceramic plate with the single crystal wafer was then placed in the support pad cavity of the polishing machine (close to the ceramic plate), fixed, the coarse polishing solution shown in Table 3 was first used in the polishing equipment, the single crystal wafer was polished for 60 minutes under the coarse polishing conditions shown in Table 2, after being washed with deionized water (resistivity greater than 17.5 megohm-cm at 25°C) and dried, the fine polishing solution shown in Table 3 was used in the polishing equipment, the single crystal wafer was polished for 6 minutes under the fine polishing conditions shown in Table 3, then the ceramic plate with the single crystal wafer was taken out and placed on a heating furnace, the glue was melted, the single crystal wafer was removed from the ceramic plate, washed with deionized water and dried.

[0128] Cleaning: a) at 10°C, the single crystal wafer was immersed in an aqueous solution containing 0.3% by weight of NH3 and 1.3% by weight of hydrogen peroxide for 5 minutes; b) at 10°C, the surface of the single crystal wafer was rinsed with deionized water for 3 minutes; c) at 20°C, the single crystal wafer was immersed in a 10% by weight hydrogen peroxide solution for 5 minutes; d) at 15°C, the surface of the single crystal wafer was rinsed with deionized water for 3 minutes; e) at 20°C, the single crystal wafer was immersed in a 10% by weight ammonia solution for 5 minutes; f) at 15°C, the surface of the single crystal wafer was rinsed with deionized water for 3 minutes; g) the single crystal wafer was placed in a wafer spin-dryer and dried with hot nitrogen.

[0129] The thickness of the obtained indium phosphide single crystal wafer was 650 μm, and the performance test results of the indium phosphide single crystal wafers of each example are shown in Table 4 below, wherein the carrier concentration was tested by a Hall instrument.

[0130] Table 2 Composition of coarse polishing solution and polishing conditions

[0131]

[0132] Table 3 Composition of fine polishing solution and polishing conditions

[0133]

[0134] Table 4 Performance test results of indium phosphide single crystal wafers

[0135]

[0136] The data in Table 4 show that the InP single crystal wafers cut from the zinc and iron 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 requirements of industrial applications such as optoelectronic devices and electronic devices.

[0137] While the foregoing has been described in some detail for purposes of clarity and the appropriate direction of the present application, it will be appreciated by those skilled in the art that various changes in form and detail can be made without departing from the principles and scope of the application. All references, including publications, patents, and standards, cited herein are hereby incoφorated by reference in their entirety.

Claims

1. An indium phosphide crystal which is a P-type indium phosphide single crystal, said indium phosphide crystal containing 0.5 ppm to 500 ppm of zinc element, and further containing 0.02 ppm to 50 ppm of iron element.

2. The indium phosphide crystal according to claim 1, wherein the content of the zinc element 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 content of the iron element is 0.03 ppm to 40 ppm, preferably 0.03 ppm to 20 ppm, more preferably 0.03 ppm to 10 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 x 1014cm-3 to 5 x 1014cm-3, for example 1 x 1014cm-3 to 1 x 1015cm-3, preferably 1 x 1014cm-3 to 8 x 1014cm-3, or for example 8 x 1014cm-3 to 9 x 1014cm-3, preferably 9 x 1014cm-3 to 8 x 1015cm-3. 17 cm -3 19 cm -3 18 cm -3 19 cm -3 18 cm -3 18 cm -3 17 cm -3 18 cm -3 17 cm -3 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 boule.

6. A method for producing an indium phosphide crystal, wherein the indium phosphide crystal is a P-type indium phosphide single crystal, said method comprising the steps of: charging a growth container, such as a crucible, provided with a seed crystal, with phosphorus, indium phosphide polycrystal, a dopant containing iron element, and a dopant containing zinc element or a dopant containing both zinc and iron, together with a sealing agent; and placing the container in a crystal growth furnace and heating to a temperature above the melting point of indium phosphide.

7. The method according to claim 6, wherein the method is selected from the group consisting of vertical Bridgman method (VB), vertical gradient freeze method (VGF), vapor pressure controlled Czochralski method (VCZ), or vertical crucible growth method.

8. An indium phosphide single crystal wafer produced from the indium phosphide crystal according to any one of claims 1 to 5 or produced from the indium phosphide crystal obtained by the method according to any one of claims 6 to 7.

9. An electronic or optoelectronic device produced from the indium phosphide single crystal wafer according to claim 8 or containing a component produced from the indium phosphide single crystal wafer according to claim 8.

10. Use of a combination of a dopant containing iron element and a dopant containing zinc element or a dopant containing both zinc and iron in the production of an indium phosphide crystal for reducing dislocation density, reducing twin defects, and / or increasing yield of indium phosphide crystal product while increasing carrier concentration. ​

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