SURFACE PHOTOVOLTAGE SPECTROSCOPY OF INXAL1-XAS EPILAYERS

The surface and interface electronic structure of mismatched InxAl1-xA s epitaxial layers grown by molecular beam epitaxy on InP have been in vestigated using surface photovoltage spectroscopy. The crystalline st ructure of the epilayers was also examined by double-crystal x-ray dif fraction. For coherently strained layers, only a few gap states are id entified. Highly strained samples with inferior crystalline quality, a s judged by a broadened x-ray diffraction peak and the absence of Pend ellosung fringes, display a rich spectrum of states in the band gap. S ome of the states are close to the surface while others are located in the vicinity of the InAlAs/InP heterointerfaces. (C) 1995 American In stitute of Physics.