Bulk single crystal gallium nitride and method of making same

Abstract

A single crystal M*N article, which may be made by a process including the steps of: providing a substrate of material having a crystalline surface which is epitaxially compatible with M*N; depositing a layer of single crystal M*N over the surface of the substrate; and removing the substrate from the layer of single crystal M*N, e.g., with an etching agent which is applied to the substrate to remove same, to yield the layer of single crystal M*N as said single crystal M*N article. The bulk single crystal M*N article is suitable for use as a substrate for the fabrication of microelectronic structures thereon, to produce microelectronic devices comprising bulk single crystal M*N substrates, or precursor structures thereof.

What is claimed is:  
     
         1 . A method of making a single crystal M*N article, including the steps of: 
 providing a substrate of material having a crystalline surface which is epitaxially compatible with M*N,    depositing a layer of single crystal M*N over a surface of the substrate; and    removing the substrate from the layer of single crystal M*N while the crystal is close to the growth temperature, to recover the layer of single crystal M*N as a single crystal M*N article.    
     
     
         2 . A method according to    claim 1   , wherein the substrate of crystalline material is formed of a material selected from the group consisting of silicon, silicon carbide, and gallium arsenide, and the substrate is etchably removed from the layer of single crystal M*N at or near the growth temperature, by etching of the substrate using a gas which etches the substrate material but does not etch the single crystal M*N material.  
     
     
         3 . A method according to    claim 1   , wherein the layer of single crystal M*N is deposited directly on said surface of the substrate.  
     
     
         4 . A method according to    claim 1   , wherein an intermediate layer of epitaxially related crystalline material is formed directly on said surface of the substrate, and the layer of single crystal M*N is deposited directly on an upper surface of the intermediate layer.  
     
     
         5 . A method according to    claim 4   , wherein the intermediate layer of epitaxially related crystalline material comprises a protective layer deposited thereon prior to growth of the M*N layer, so that the protective layer will prevent decomposition of the single crystal substrate while M*N growth is proceeding.  
     
     
         6 . A method according to    claim 4   , wherein the intermediate layer of epitaxially related crystalline material is formed either in situ or ex situ.  
     
     
         7 . A method according to    claim 4   , wherein the intermediate layer of epitaxially related crystalline material includes an etch stop layer.  
     
     
         8 . A method according to    claim 1   , wherein the substrate material comprises a material selected from the group consisting of silicon, silicon carbide, gallium arsenide and sapphire, MgAl 2 O 4 , MgO, ScAlMgO 4 , LiAlO 2 , LiGaO 2 , ZnO, graphite, glass, M*N, SiO 2 , twist-bonded substrate structures, silicon-on-insulator (SOI) substrates, compliant substrates, and substrates containing buried implant species.  
     
     
         9 . A method according to    claim 4   , wherein the intermediate layer of epitaxially related crystalline material comprises a strained layer superlattice comprising from 5 to 100 alternating monolayers of two materials selected from the group consisting of AlN, InN, GaN and alloys of SiC with one or more of AlN, InN, and GaN.  
     
     
         10 . A method according to    claim 1   , wherein the substrate has a similar thermal coefficient of expansion to the M*N layer.  
     
     
         11 . A method according to    claim 1   , wherein the substrate crystalline material or a component of the substrate crystalline material is diffused out of the substrate into the M*N layer, for incorporation of the substrate crystalline material or a component thereof in the M*N layer as a dopant thereof.  
     
     
         12 . A method according to    claim 11   , wherein the substrate crystalline material comprises silicon and wherein the silicon substrate is etchably removed with HCl gas to yield the M*N layer having a silicon-doped M*N surface region for formation of ohmic contacts thereon.  
     
     
         13 . A method according to    claim 1   , wherein the layer of single crystal M*N comprises a GaN layer.  
     
     
         14 . A method according to    claim 1   , wherein the layer of single crystal M*N comprises an MGaN layer, wherein M is a metal compatible with Ga and N in the composition MGaN, and the composition MGaN is stable at standard temperature and pressure (25° C. and 1 atmosphere pressure) conditions.  
     
     
         15 . A method according to    claim 14   , wherein M is selected from the group consisting of Al and In.  
     
     
         16 . A method according to    claim 1   , where M*N is selected from the group consisting of GaN, SiC and alloys of SiC with one or more of AlN, GaN and InN.  
     
     
         17 . A method according to    claim 1   , wherein hydrogen is implanted in the substrate, so that during the deposition of M*N on the substrate, the hydrogen causes in situ fracture of the substrate to separate the substrate from the layer of M*N.  
     
     
         18 . A method according to    claim 1   , where the single crystal M*N layer comprises a compositionally graded ternary metal nitride selected from the group consisting of AlGaN, InGaN, and AlInN.  
     
     
         19 . A method according to    claim 1   , where the single crystal M*N layer is doped.  
     
     
         20 . A method according to    claim 19   , wherein the single crystal M*N layer is doped with a dopant selected from the group consisting of Si, Ge, S, Se, Mg, Zn, Be, V, and Fe.  
     
     
         21 . Bulk single crystal M*N.  
     
     
         22 . Bulk single crystal GaN.  
     
     
         23 . Bulk single crystal MGaN, wherein M is a metal compatible with Ga and N in the composition MGaN, and the composition MGaN is stable at standard temperature and pressure (25° C. and 1 atmosphere pressure) conditions.  
     
     
         24 . Bulk single crystal MGaN according to    claim 23   , wherein M is selected from the group consisting of Al and In.  
     
     
         25 . Bulk single crystal MM′GaN, wherein M and M′ are metals compatible with Ga and N in the composition MM′GaN, and the composition MM′GaN is stable at standard temperature and pressure (25° C. and 1 atmosphere pressure) conditions.  
     
     
         26 . A bulk single crystal M*N article of cylindrical or disc-shaped form wherein the diameter is at least 200 micrometers and the thickness is at least 1 micrometer.  
     
     
         27 . A bulk single crystal M*N article of cylindrical or disc-shaped form, having a thickness of at least 100 micrometers and the diameter is at least 2.5 centimeters.  
     
     
         28 . A bulk single crystal M*N article according to    claim 21   , wherein the bulk single crystal M*N comprises a surface having a microelectronic device structure or substructure formed thereon.  
     
     
         29 . A bulk single crystal M*N article according to    claim 21   , comprising a doped surface region.  
     
     
         30 . A bulk single crystal M*N article according to    claim 29   , wherein the doped surface region comprises silicon-doped M*N.  
     
     
         31 . A bulk single crystal M*N article according to    claim 30   , wherein the silicon-doped surface region has an ohmic contact structure fabricated thereon.  
     
     
         32 . A bulk single crystal M*N article according to    claim 21   , where the single crystal M*N comprises a compositionally graded ternary metal nitride selected from the group consisting of AlGaN, InGaN, and AlInN.  
     
     
         33 . A bulk single crystal M*N article according to    claim 21   , wherein the single crystal M*N is doped with a dopant selected from the group consisting of Si, Ge, S, Se, Mg, Zn, Be, V, and Fe.  
     
     
         34 . A bulk single crystal M*N article according to    claim 21   , wherein the single crystal M*N is n-doped.  
     
     
         35 . A bulk single crystal M*N article according to    claim 21   , wherein the single crystal M*N is p-doped.  
     
     
         36 . A bulk single crystal M*N article according to    claim 21   , wherein the single crystal M*N is semi-insulatively-doped.  
     
     
         37 . A microelectronic structural assembly, comprising a bulk single crystal GaN substrate having fabricated thereon a microelectronic device or a device precursor structure thereof.  
     
     
         38 . A microelectronic structural assembly according to    claim 37   , comprising a microelectronic device selected from the group consisting of LEDs, lasers, detectors, and transistors, and device precursor structures thereof.