Effect of Cycle Annealing Parameters on Dislocation Density Reduction for HgCdTe on Si

Abstract

In our previous study of ex situ thermal cycle annealing (TCA) of molecular beam epitaxy (MBE)-grown mercury cadmium telluride (HgCdTe) on CdTe/Si(211) composite substrates we showed consistent dislocation density reduction to ~1 × 106 cm−2. In this work, we have extended our study to understand the effects of TCA at lower temperatures and fewer cycles than studied previously. By examining TCA performed at the lower end of the temperature spectrum (as low as 385°C), we are able to show an exponential correlation between etch pit density (EPD) and temperature. Varying the number of cycles also shows a similar exponential correlation with EPD. These results suggest that these are the two major factors driving dislocation annihilation and/or coalescence. In this paper, we discuss the theoretical mechanism behind dislocation reduction, both at the surface and throughout the bulk of the HgCdTe layer.