Techniques for forming optoelectronic devices

Abstract

Embodiments relate to use of a particle accelerator beam to form thin films of material from a bulk substrate are described. In particular embodiments, a bulk substrate having a top surface is exposed to a beam of accelerated particles. In certain embodiments, this bulk substrate may comprise GaN; in other embodiments this bulk substrate may comprise (111) single crystal silicon. Then, a thin film or wafer of material is separated from the bulk substrate by performing a controlled cleaving process along a cleave region formed by particles implanted from the beam. In certain embodiments this separated material is incorporated directly into an optoelectronic device, for example a GaN film cleaved from GaN bulk material. In some embodiments, this separated material may be employed as a template for further growth of semiconductor materials (e.g. GaN) that are useful for optoelectronic devices.

What is claimed is: 
     
         1 . A workpiece for formation of an optoelectronic device, the workpiece comprising:
 a layer of crystalline material having a lattice constant compatible with formation of an overlying film of semiconductor material; and   a substrate releasably bonded to a first surface of the layer of crystalline material opposite to a second surface of the layer of crystalline material, the second surface being coarse from cleaving and whereupon the overlying film of semiconductor material is to be formed,   wherein the substrate has a coefficient of thermal expansion approximately equal to a coefficient of thermal expansion of the layer of crystalline material.   
     
     
         2 . The workpiece as in  claim 1  wherein the layer of crystalline material exhibits a level of stress lower than a threshold value sufficient to nucleate and propagate defects within the layer of crystalline material. 
     
     
         3 . The workpiece as in  claim 1  wherein mismatch between the substrate and the layer of crystalline material develops the level of stress insufficient to generate more than about 1×10 4  defects/cm 2 . 
     
     
         4 . The workpiece as in  claim 1  wherein mismatch between the substrate and the layer of crystalline material develops the level of stress insufficient to generate more than 1×10 6  defects/cm 2 . 
     
     
         5 . The workpiece as in  claim 1  wherein the layer of crystalline material comprises a non-thermal stress relaxed material. 
     
     
         6 . The workpiece as in  claim 1  wherein the layer of crystalline material comprises GaN and the substrate comprises metal. 
     
     
         7 . The workpiece as in  claim 6  wherein a coefficient of thermal expansion of the metal substrate is approximately equal to a coefficient of thermal expansion of the GaN at a temperature range of between about 900-1200° C. 
     
     
         8 . The workpiece as in  claim 1  wherein the substrate is releasably bonded to the layer of crystalline material based upon a roughness of the substrate and/or a roughness of the layer of crystalline material. 
     
     
         9 . The workpiece as in  claim 1  wherein the substrate is releasably bonded to the layer of crystalline material based upon an intervening sacrificial layer. 
     
     
         10 . The workpiece as in  claim 9  wherein the intervening sacrificial layer comprises an oxide. 
     
     
         11 . A method comprising:
 providing a workpiece bearing a layer of additional material;   introducing a plurality of particles through the layer of additional material to form a cleave region in the workpiece;   applying energy to cleave a detached thickness of workpiece material including the layer of additional material, from a remainder of the workpiece, and forming a free standing intermediate structure that includes the detached workpiece material and the layer of additional material;   processing the layer of additional material of the intermediate structure; and   bonding the processed layer of additional material to a substrate having a coefficient of thermal expansion approximately equal to a coefficient of thermal expansion of the layer of additional material.