Effects of growth temperature and surface treatment on growth orientation and interface structure during molecular beam epitaxy of CdTe on (0 0 1)GaAs

The effects of growth temperature and substrate surface treatment on the growth orientation and interface structure during molecular beam epitaxy of CdTe on (0 0 1)GaAs have been investigated using cross-sectional high-resolution electron microscopy. It has been observed that the substrate preheating at 600°C for 5 min without conventional chemical etching is sufficient to remove the native oxide layer. For the growth temperature near 300° C, (1 1 1) growth was dominant at lower growth temperatures whereas (0 0 1) growth at higher temperatures. At a certain temperature, 290°C in this experiment, the growth orientation was not determined only by growth temperature, but seemed to be determined by substrate surface treatments prior to growth, such as chemical etching and substrate preheating at 600°C. It has been observed that the chemical etching caused etch pits and roughening of substrate surface and that it enhanced the (0 0 1) nucleation and growth in the etch pits, so that the (0 0 1) growth with chemical etching could happen at lower growth temperatures than those without chemical etching.