Green photoluminescence from cubic In0.4Ga0.6N grown by radio frequency plasma-assisted molecular beam epitaxy

We investigate the structural and optical properties of a cubic (In, Ga)N/G aN/(Al, Ga)N heterostructure containing a 185 nm thick In0.4Ga0.6N layer wh ich dominates the optical properties of the sample. The phase purity of the structure is verified by means of transmission electron microscopy while t he In content is measured by x-ray diffraction and secondary ion mass spect rometry. The room-temperature band gap of the In0.4Ga0.6N layer is determin ed by transmission and reflectance measurements to be 2.46 +/- 0.03 eV. Thi s value agrees with the spectral position of the dominating green photolumi nescence at 300 K. (C) 1998 American Institute of Physics. [S0003-6951(98)0 0735-9].