▎ 摘　　要

NOVELTY - A silicon/graphene composite substrate comprises silicon substrate, graphene layer and gallium nitride nano-column from bottom to top, where the silicon/graphene composite substrate is epitaxially grown on gallium nitride nanopillar. USE - Silicon/graphene composite substrate for preparing semiconductor laser, light emitting diode or solar cell and photohydrolysis of water to hydrogen (all claimed). ADVANTAGE - The silicon/graphene composite substrate has high orderliness and quality, low defect density and enhanced composite and luminous efficiency, and can be prepared in simple and rapid manner. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) a method for preparing a silicon/graphene composite substrate, which involves cleaning a silicon substrate, preparing a graphene layer on a silicon substrate and the high-temperature growth of gallium nitride nano-pillars on a graphene layer of a silicon substrate by molecular beam epitaxy at a high temperature of 900-1100 degrees C, where the gallium nitride nano-pillar is continuously grown at a low temperature by molecular beam epitaxy and the temperature at a low temperature is 650-800 degrees C (2) use of silicon/graphene composite substrate for producing semiconductor laser, light emitting diode or solar cell..