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 metalorganic 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 results of atomic force microscopy, reflection high-energy electron diffraction, and X-ray diffraction. Chemical and thermal treatments of the Si substrate 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 photoluminescence ascribed to the donor acceptor pair emission at a low temperature, 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 substrate with a total thickness of 1.25 mum shows bright electroluminescence, indicating a tough nature against the large lattice mismatch. The preliminary GaAsP pn junctions on Si showed infrared and visible luminescence at room temperature.