Numerical simulation of the growth of HgCdTe layers by liquid phase epitaxy from Te-rich solutions: The effect of liquid dimensions and mercury loss

Abstract

A diffusion based model of the slider method of the liquid phase epitaxy (LPE) process of HgCdTe in the Te-rich region of the phase diagram is presented. The effects of changes of density, mercury loss, moving solid-liquid interface and liquid finite dimensions are explicitly considered in the numerical calculations. A numerical description of the phase diagram by two polynomial expressions, derived from the experimental data of Harman, has been used. Step cooling, ramp cooling and supercooling processes are studied. The obtained epilayers behave as Hsieh theory predicts for binary liquids for short growth time in the absence of mercury leaks, except for the composition profile obtained. Our results are in qualitative agreement with those reported by Shaw in an earlier paper for such binary system, but differ on the layer composition and thickness. For processes longer than a characteristic time, related to the liquid thickness, the growth rate decreases and, if mercury loss is present, the composition of the grown layer becomes richer in cadmium. The effect of mercury loss is very pronounced in step cooling and supercooling processes with small cooling rates. If the dimensions and the mercury loss flux of a system are known the resulting epilayers can be simulated. A good agreement is found when the model is applied to experimental data.