A review of the synthesis of reduced defect density In_xGa_1−xN for all indium compositions

A review of metal rich and nitrogen rich (N-rich), low-temperature grown In_xGa_1−xN is provided, focusing on two low-temperature approaches that have resulted in non-phase separated In_xGa_1−xN. The metal modulated epitaxy (MME) and N-rich, low temperature approaches to the reduction of defects in In_xGa_1−xN are described and are capable of growing In_xGa_1−xN throughout the miscibility gap. MME films remain smooth at all thicknesses but show device quality material primarily for x < 0.2 and x > 0.6. Low temperature, N-rich grown films show a critical thickness extend well beyond the theoretical values and results in slower relaxation through the 0.2 < x < 0.6 range most interesting for light emitters and solar cells. This reduced defect density results in improved optical emission, but due to increased roughening with increased thickness, low temperature, N-rich films are limited to thin layers. Future thick In_xGa_1−xN substrates are necessary to increase design freedom, as well as improve optoelectronic device performance. Initial results with films up to 800 nm are shown to display evidence of defect annihilation which could be promising for future thick optoelectronic templates and thick devices.