Gas-source molecular beam epitaxial growth, characterization, and light-emitting diode application of In_xGa_1-xP on GaP(100)

Highly lattice-mismatched InxGa1-xP (x≤0.38) layers were grown on GaP substrates by gas-source molecular beam epitaxy. A relatively thin, compositionally linear-graded buffer layer was used to reduce the number of threading dislocations. Studies by double-crystal x-ray diffraction and transmission electron microscopy show this buffer layer to be 97% strain-relaxed along both 〈110〉 directions with dislocations well confined within the graded buffer and the substrate. Threading dislocation densities in the top layers were less than 1×107 cm -2. Room-temperature photoluminescence, ranging from 560 to 600 nm, is achieved. Heterojunction p-i-n diodes emitting at 560 nm at 300 K exhibit good rectifying and reverse breakdown characteristics.