Solid solution wide bandgap semiconductor materials

Abstract

A substrate and method for growing a semi-conductive crystal on an alloy film such as (AIN) x (SiC) (1-x) without any buffer layer is disclosed. The (AIN) x (SiC) (1-x) alloy film can be formed on a SiC substrate by a vapor deposition process using AIN and SiC powder as starting materials. The (AIN) x (SiC) (1-x) alloy film provides a better lattice match for GaN or SiC epitaxial growth and reduces defects in epitaxially grown GaN with better lattice match and chemistry.

1 . An alloy film formed on a substrate, said alloy film has a formula of (AIN) x (SiC) (1-x)  or Si x Ge (1-x) C, where 0<x<1. 
     
     
         2 . The alloy film of  claim 1 , wherein x≧0.7. 
     
     
         3 . The alloy film of  claim 1 , wherein x≦0.5. 
     
     
         4 . The alloy film of  claim 1 , wherein said substrate is SiC. 
     
     
         5 . The alloy film of  claim 1 , wherein said substrate is 6H-SiC. 
     
     
         6 . A process for forming the alloy film of  claim 1 , comprising:
 depositing said film on the substrate by a vapor deposition method.   
     
     
         7 . The method of  claim 6 , wherein the substrate comprises SiC. 
     
     
         8 . The method of  claim 7 , wherein the substrate comprises on-axis 6H-SiC 
     
     
         9 . The method of  claim 6 , wherein the vapor deposition method is selected from the group consisting of physical vapor transport (PVT), advanced PVT (APVT), chemical vapor deposition (CVD) and metal-organic chemical vapor deposition (MOCVD). 
     
     
         10 . The method of  claim 6 , further comprising the step of:
 doping the substrate prior to forming the alloy film on the substrate.   
     
     
         11 . The method of  claim 6 , wherein the substrate comprises SiC and is doped with ammonia or trimethyl aluminum in an MOCVD process. 
     
     
         12 . The method of  claim 6 , further comprising the step of:
 treating the substrate with hexamethyldisilizane and ammonia prior to forming the alloy film on the substrate.   
     
     
         13 . The method of  claim 6 , wherein said alloy film is formed by PVT using SiC and AIN powders as starting materials. 
     
     
         14 . The method of  claim 13 , wherein said PVT is performed under a background pressure of less than 100 torr. 
     
     
         15 . The method of  claim 13 , wherein said PVT is performed under a background pressure of 400-500 torr. 
     
     
         16 . The method of  claim 13 , wherein said PVT is performed under a background pressure of 1-200 torr and at an AIN-to-SiC ratio in the range of 1:1 to 5:1. 
     
     
         17 . The method of  claim 13 , wherein said PVT is performed under a background pressure of 300-500 torr and at an AIN-to-SiC ratio in the range of 1:5 to 1:1. 
     
     
         18 . The method of  claim 13 , wherein said PVT is performed with an AIN-to-SiC ratio of 1:1. 
     
     
         19 . The method of  claim 13 , wherein said PVT is performed under a background pressure of 1-500 torr and at a temperature range of about 1600° C. to 2100° C. 
     
     
         20 . The method of  claim 19 , wherein said PVT is performed at a temperature range of about 1800° C. to 1900° C.