A study of the initial epitaxial growth behavior of CdTe thin films on GaAs (100), (211), and (111) substrates by molecular dynamics simulations

CdTe materials are highly valued for their remarkable properties and wide-ranging applications. As an efficient and cost-effective technique, vapor deposition is well-suited for preparing CdTe films. In this study, molecular dynamics simulations were used to compare the early growth stages of CdTe films on GaAs (211), (111), and (100) substrates. The results showed that all films followed the Volmer-Weber (VW) growth mode. Notably, a (133)-oriented film was successfully grown on the (211) substrate, and this was confirmed by calculations. It was also observed that the interfaces of the (100) and (211) substrates had a higher density of inter-facial misfit dislocations. In contrast, the (111)-oriented film, while having a lower dislocation density, exhibited significant twinning parallel to the growth surface. This phenomenon might be attributed to the fact that the (111) plane serves as a slip plane in the zinc-blender structure. Among the three substrate orientations, both (100) and (211) demonstrated superior crystalline quality. It is hypothesized that the ease of forming misfit dislocations via slip might be a key factor in determining the crystalline quality of the films. Additionally, the (100) orientation exhibited the fastest growth rate, making it the most suitable choice for vapor deposition processes. However, the (111) film showed poorer crystalline quality due to the presence of a disordered edge region, indicating that further optimization of its growth process is necessary. One potential solution could involve depositing at an inclined angle. Furthermore, these findings suggest that selecting a growth orientation that readily forms inter-facial dislocations through slip may be beneficial during film growth.