GaAsP pn diode on Si substrate grown by metalorganic molecular beam epitaxy for visible light-emitting devices

Luminescent GaAs1-xPx (0.2 < x < 0.7) was grown on a Si substrate by metalo rganic molecular beam epitaxy (MOMBE). The insertion of a GaP buffer layer grown at a low temperature was essential to obtain luminescent GaAsP on Si. The growth condition of the GaP buffer layer was optimized based on the re sults of atomic force microscopy, reflection high-energy electron diffracti on, and X-ray diffraction. Chemical and thermal treatments of the Si substr ate were also carefully examined to obtain a flat surface and a sharp X-ray rocking curve of the GaAsP epilayer. The GaAsP epilayer on Si emits photol uminescence ascribed to the donor acceptor pair emission at a low temperatu re, and to a band-edge emission at room temperature. The GaAsP epilayer was doped for both n- and p-types with carrier concentrations up to 2 x 10(18) and 6 x 10(19) cm(-3), respectively. A GaAsP pn junction on a Gap substrat e with a total thickness of 1.25 mum shows bright electroluminescence, indi cating a tough nature against the large lattice mismatch. The preliminary G aAsP pn junctions on Si showed infrared and visible luminescence at room te mperature.