Order–Disorder Phenomena and Their Effects on Bandgap in ZnSnP2

Abstract

A ternary compound semiconductor ZnSnP2 has the order–disorder transition, where the ordered and disordered phases are chalcopyrite (I42d, a = 5.651 A, c = 2a) and sphalerite (F43m, a = 5.651 A), respectively. In this study, the quantitative relationship between bandgap and long-range order parameter η was investigated by analyzing ZnSnP2 bulk crystals obtained by various cooling rates in crystal growth. The Chipman and Warren method was used to evaluate the long-range order parameters from X-ray difffaction profiles. The results showed that the long-range order parameter η decreases from 0.94 to 0.54 with the increase in cooling rates, and the bandgap gradually reduced from 1.60 to 1.37 eV, corresponding to the η value. It was also demonstrated that bandgap tuning of ZnSnP2 was possible by controlling the long-range order parameter through annealing process. This study clarified the effects of the order–disorder phenomena on bandgap in a model material, ZnSnP2, based on the evaluation of long-range ord...