Heterostructure for electronic power components, optoelectronic or photovoltaic components

Abstract

The present invention relates to a support for the epitaxy of a layer of a material of composition Al x In y Ga (1-x-y) N, where 0≦x≦1, 0≦y≦1 and x+y≦1, having successively from its base to its surface; a support substrate, a bonding layer, a monocrystalline seed layer for the epitaxial growth of the layer of material Al x In y Ga (1-x-y) N. The support substrate is made of a material that presents an electrical resistivity of less than 10 −3 ohm·cm and a thermal conductivity of greater than 100 W·m −1 ·K −1 . The seed layer is in a material of the composition Al x In y Ga (1-x-y) N, where 0≦x≦1, 0≦y≦1 and x+y≦1. The seed and bonding layers provide a specific contact resistance that is less than or equal to 0.1 ohm·cm −2 , and the materials of the support substrate, the bonding layer and the seed layer are refractory at a temperature of greater than 750° C. or even greater than 1000° C. The invention also relates to methods for manufacturing the support.

1 . A support for the epitaxial growth of a layer of a material, which comprises:
 a support substrate that includes a bonding layer;   a monocrystalline seed layer on the bonding layer made of a material and having properties sufficient to facilitate epitaxial growth of an active layer of Al x In y Ga (1-x-y) N, where 0≦x≦1, 0≦y≦1 and x+y≦1;   wherein the seed layer and bonding layer comprise materials that provide a specific contact resistance therebetween that is less than or equal to 0.1 ohm·cm −2 , and the support substrate, the bonding layer and the seed layer each comprises a material that is refractory at a temperature of greater than 750° C.   
     
     
         2 . The support of  claim 1 , wherein the support substrate has an electrical resistivity of less than 10 −3  ohm·cm and a thermal conductivity of greater than 100 W·m −1 ·K −1 . 
     
     
         3 . The support of  claim 1 , wherein the support substrate comprises a refractory metal selected from the group consisting of tungsten, molybdenum, niobium or tantalum and their binary, ternary or quaternary alloys. 
     
     
         4 . The support of  claim 3 , wherein the metal alloys are TaW, MoW, MoTa, MoNb, WNb or TaNb. 
     
     
         5 . The support of  claim 4  wherein the metal allow is TaW comprising at least 45% tungsten or MoTa comprising more than 65% molybdenum. 
     
     
         6 . The support of  claim 1 , wherein the bonding layer comprises a material comprising polycrystalline silicon, a silicide, a refractory metal, a metal boride, zinc oxide, or indium tin oxide. 
     
     
         7 . The support of  claim 1 , wherein the bonding layer comprises a material having an electrical resistivity of less than or equal to 10 −4  ohm·cm. 
     
     
         8 . The support of  claim 1 , wherein the seed layer has an electrical resistivity of between 10 −3  and 0.1 ohm·cm. 
     
     
         9 . A heterostructure for the manufacture of electronic power components, optoelectronic components or photovoltaic components comprising:
 the support of  claim 1 , wherein the material of seed layer is Al x In y Ga (1-x-y) N, where 0≦x≦1, 0≦y≦1 and x+y≦1;   an active layer expitaxially grown on the seed layer is crack-free and is made of a material having a composition of Al x In y Ga (1-x-y) N, where 0≦x≦1, 0≦y≦1 and x+y≦1, with a thickness of between 3 and 100 micrometers and a dislocation density of less than 10 8  cm −2 .   
     
     
         10 . The heterostructure of  claim 9 , wherein the seed layer and active layer comprise materials that provide a difference in lattice parameter of less than 0.005 Å, and the active layer comprises a main portion in which the thickness represents between 70 and 100% of the thickness of the active layer and in which the concentration of dopants is less than or equal to 10 17  cm −3 . 
     
     
         11 . The heterostructure of  claim 9 , wherein the support substrate comprises a material that provides a CTE that is between a minimum value that is less than 0.5·10 −6  K −1  below the CTE of the material of the main portion of the active layer and a maximum value that is no more than 0.6·10 −6  K −1  above the CTE of the material of the main portion of the active layer at the temperatures used for epiaxially forming the active layer. 
     
     
         12 . The heterostructure of  claim 9 , wherein the main portion of the active layer is inserted between a subjacent portion and a superjacent portion, and wherein the subjacent and superjacent portions each comprise a concentration of dopants greater than 10 17  cm −3 , wherein the main portion, the subjacent portion and the superjacent comprises GaN and the dopant of the superjacent portion is different from the dopant of the subjacent layer. 
     
     
         13 . The heterostructure of  claim 9 , wherein the main portion of the active layer is inserted between a subjacent portion and a superjacent portion, and wherein the material of the main portion is of a different Al x In y Ga (1-x-y) N composition than the subjacent portion and the superjacent portion of the active layer, and the composition of the subjacent portion is different from the composition of the superjacent portion. 
     
     
         14 . The heterostructure of  claim 9 , wherein the thickness of the main portion represents 100% of the thickness of the active layer and that the material of the main portion is of doped n type GaN, or wherein the support substrate comprises molybdenum, the bonding layer is tungsten, the seed layer is GaN. 
     
     
         15 . An electronic power, optoelectronic or photovoltaic component formed in or on the active layer of a heterostructure according  claim 1 , and comprising at least one electrical contact on the active layer and at least one electrical contact on the support substrate 
     
     
         16 . A method of manufacturing a support for the epitaxy of a layer of material which comprises:
 forming a bonding layer upon one of a donor substrate or a support substrate, or on both;   bonding the donor substrate to the support substrate such that the bonding layer is situated between the donor substrate and the support substrate at an interface; and   removing a portion of the donor substrate to leave a seed layer on the support substrate for epitaxial growth of an active layer, wherein the donor substrate, the support substrate and the bonding layer are refractory materials having a temperature greater than 750° C. or greater than 1000° C. and chosen to provide a specific contact resistance between the seed layer and the bonding layer that is less than or equal to 0.1 ohm·cm −2 .   
     
     
         17 . The method of  claim 16 , wherein the support substrate has an electrical resistivity of less than 10 −3  ohm·cm −1  and a thermal conductivity of greater than 100 W·m −1 ·K −1 . 
     
     
         18 . The method of  claim 16 , wherein the seed layer comprises a monocrystalline material layer adapted for the epitaxial growth of a material of composition Al x In y Ga (1-x-y) N, where 0≦x≦1, 0≦y≦1 and x+y≦1 
     
     
         19 . The method of  claim 16 , which further comprises implanting ions into the donor substrate to form an embrittlement zone at a depth that is substantially equal to the thickness of the seed layer to be left on the support substrate after removing the portion of the donor substrate. 
     
     
         20 . The method according to  claim 19 , wherein the implanting is carried out after the formation of the bonding layer on the donor substrate, and through the bonding layer. 
     
     
         21 . The method of  claim 16 , which further comprises:
 measuring the surface roughness of the donor substrate and support substrate; and   depositing a bonding layer on the surface of either or both substrates that have a roughness greater than 1 nm for a 5 micrometer×5 micrometer surface measured by AFM and a peak valley surface topology of greater than or equal to 10 nm.   
     
     
         22 . The method of  claim 16 , which further comprises epitaxially growing an active layer on the seed layer to a thickness of between 3 and 100 micrometers without cracking to form a heterostructure. 
     
     
         23 . The method of  claim 22 , which further comprises providing the active layer with a main portion whose thickness represents between 70 and 100% of the thickness of the active layer and whose concentration of dopants is less than or equal to 10 17  cm −3 . 
     
     
         24 . The method of  claim 22 , wherein the active layer is a monocrystalline layer, and has a composition of Al x In y Ga (1-x-y) N, where 0≦x≦1, 0≦y≦1 and x+y≦1. 
     
     
         25 . The method of  claim 22 , which further comprises choosing the material of the support substrate such that the coefficient of thermal expansion (CTE) of the support substrate material is between a minimum value that is less than 0.5·10 −6  K −1  below the CTE of the material of the main portion of the active layer and a maximum value that is no more than 0.6·10 −6  K −1  above the CTE of the material of the main portion of the active layer at the temperatures used for epiaxially forming the active layer.