Atomic force microscopy studies of CdTe films grown by epitaxial lateral overgrowth

Epitaxial lateral overgrowth (ELO) of CdTe was carried out on GaAs using silicon nitride as the mask material. Windows were delineated on silicon, nitride mask deposited on GaAs substrates and CdTe was grown using metalorganic vapor phase epitaxy. The films were characterized by atomic force microscopy (AFM). It has been shown that highly selective growth of CdTe can be achieved at temperatures higher than 500 C and pressures lower than 25 torr using silicon nitride as the mask layer. Optimizing the growth conditions as well as the stripe directions on the substrates enables the growth of ELO-CdTe with a flattop surface and vertical sidewalls. AFM studies show that ELO-grown CdTe contains large grains with reduced defect densities, but there seems to be no difference on the films grown on the window region or on the masked region. The results suggest that the growth mechanism for CdTe growth on GaAs is different from that of ELO-grown GaN. A possible growth model for the patterned CdTe growth is also proposed.