Microstructure and luminescent properties of novel InGaP alloys on relaxed GaAsP substrates

摘要

We present a metal organic chemical vapor deposition (MOCVD) growth study of unconventional alloys of InGaP (with In fraction of 0.2-0.4) grown on fully relaxed GaAsP virtual substrates for the application of high performance visible light emitting diodes (LEDs) and lasers in the green to red range of the visible spectrum. Several defects which are harmful to optical performance were identified, characterized, and removed. These include CuPt-B order (which lowers band gap), phase separation or short range order (which contributes to leakage currents and reduces luminescence) and undulation of the virtual substrate surface (which prevents high quality epitaxial growth). Each of these defects is understood through a two-step growth model which describes the formation and subsequent randomization of defects during growth. Through control of MOCVD parameters including growth temperature, Ⅴ/Ⅲ ratio, growth rate, and surfactant we demonstrate growth of extremely high quality InGaP heterostructures which hold promise for fabrication of light emitting devices.