Alternative substrates for epitaxial growth

Abstract

A substrate including a base substrate, an interfacial bonding layer disposed on the base substrate, and a thin film adaptive crystalline layer disposed on the interfacial bonding layer. The interfacial bonding layer is solid at room temperature, and is in liquid-like form when heated to a temperature above room temperature. The interfacial bonding layer may be heated during epitaxial growth of a target material system grown on the thin film layer to provide the thin film layer with lattice flexibility to adapt to the different lattice constant of the target material system. Alternatively, the thin film layer is originally a strained layer having a strained lattice constant different from that of the target material system but with a relaxed lattice constant very close to that of the target material system, which lattice constant is relaxed to its relaxed value by heating the interfacial bonding layer after the thin film layer is removed from the first semiconductor substrate, so that the thin film layer has an adjusted lattice constant equal to its unstrained, relaxed value and very close to the lattice constant of the target material system.

What is claimed is:  
     
         1 . A substrate comprising: 
 a base substrate layer; and    a relaxed-strained thin film adaptive crystalline layer bonded to the base substrate layer and having a surface in-plane lattice constant different from that of the base substrate layer and close to that of a target material system.    
     
     
         2 . The substrate of  claim 1 , wherein the in-plane lattice constant is in the same range as that of In x (Al y Ga 1−y ) 1−x As wherein x is approximately 15% to approximately 45%.  
     
     
         3 . The substrate of  claim 1 , wherein the substrate comprises a substrate for formation of a vertical cavity surface emitting laser based on In x (Al y Ga 1−y ) 1−x As.  
     
     
         4 . The substrate of  claim 3 , wherein x is approximately 15% to approximately 45%.  
     
     
         5 . The substrate of  claim 1 , wherein the thin film adaptive crystalline layer comprises InGaAs having an In composition between approximately 15% and approximately 45%.  
     
     
         6 . The substrate of  claim 1 , wherein the base substrate comprises GaAs, and the thin film adaptive crystalline layer comprises In x (Al y Ga 1−y ) 1−x As.  
     
     
         7 . The substrate of  claim 6 , wherein x is approximately 15% to approximately 45%.  
     
     
         8 . The substrate of  claim 1 , wherein the thin film adaptive crystalline layer comprises a semiconductor.  
     
     
         9 . The substrate of  claim 8 , wherein the semiconductor comprises InGaAsP, GaSb, InGaAs, InGaP, AlGaP, InSb, InP, AlSb, or InAs.  
     
     
         10 . The substrate of  claim 1 , wherein the base substrate layer comprises semiconductor, an inorganic material, a metal, or a combination thereof.  
     
     
         11 . The substrate of  claim 10 , wherein the semiconductor comprises GaAs, InP, GaP, Si, or Ge.  
     
     
         12 . The substrate of  claim 10 , wherein the inorganic material comprises sapphire, poly-crystalline boron nitride, or ceramics.  
     
     
         13 . The substrate of  claim 10 , wherein the relaxed-strained thin film adaptive crystalline layer is fabricated having a strained lattice constant equal to a lattice constant of a first semiconductor substrate on which it is grown, which strained lattice constant has been adjusted by bonding the thin film adaptive layer to a carrier substrate via an interfacial bonding layer and removing the first substrate, and then heating the interfacial bonding layer to liquidize the interfacial bonding layer to allow the strained thin film adaptive layer to relax to its unstrained lattice structure to form the relaxed-strained thin film adaptive layer, and then bonding the thin film layer to the base substrate and removing the carrier substrate to expose an epitaxial growth surface of the thin film adaptive layer.  
     
     
         14 . A method of forming a substrate for formation of semiconductor devices, comprising: 
 forming a strained pseudomorphic thin film adaptive layer on a first substrate;    bonding a first surface of the thin film adaptive layer to a carrier substrate with an interfacial bonding layer;    removing the first substrate by selective etching or lift off and leaving the thin film adaptive layer; and    liquidizing the interfacial bonding layer to allow the strained pseudomorphic thin film adaptive layer to relax its unstrained lattice structure.    
     
     
         15 . The method of  claim 14 , further comprising the steps of: 
 bonding the surface of the thin film adaptive layer to a second substrate; and    removing the carrier substrate to expose a second surface of the thin film adaptive layer.    
     
     
         16 . The method of  claim 15 , further comprising treating the surface of the second substrate prior to the bonding.  
     
     
         17 . The method of  claim 14 , wherein the liquidizing comprises heating the interfacial bonding layer.  
     
     
         18 . A substrate produced in accordance with the method of  claim 14 .  
     
     
         19 . An optoelectronic apparatus, comprising: 
 a substrate comprising: 
 a thin film adaptive crystalline layer; and  
 a base substrate layer, the thin film adaptive crystalline layer bonded to the base substrate layer and having a surface in-plane lattice constant, and wherein the in-plane lattice constant is different from that of the base substrate layer, wherein the thin film adaptive crystalline layer comprises a strained pseudomorphic thin film grown on a first semiconductor substrate that is bonded to and transferred to a second carrier substrate, wherein the first semiconductor substrate is removed and the in-plane lattice constant relaxes from an original strained value to a new value close to an unstrained lattice constant, and wherein the thin film adaptive crystalline layer is physically or chemically bonded to the base substrate layer with or without an interfacial bonding layer; and  
 an optoelectronic device epitaxially grown on the thin film adaptive crystalline layer.  
   
     
     
         20 . The optoelectronic apparatus of  claim 19 , wherein the optoelectronic device is a semiconductor laser.