Strategies for dislocation density reduction in CdTe epilayers grown directly on (211) Si substrates using MOVPE

Two different techniques, namely in-situ cycle annealing and post-growth patterning and annealing, were studied to reduce dislocation density in thick CdTe epilayers grown directly on (211) Si substrates using metal organic vapor phase epitaxy (MOVPE) for their applications in X-ray, gamma ray detector development. During in-situ annealing, it was observed that annealing initiated at a later stage of growth reduced the dislocation density more effectively than annealing initiated at the early growth stage. Nonetheless, in both cases, the dislocation density was reduced compared to the unannealed samples of similar thicknesses. On the other hand, the post-growth patterning of CdTe/Si into square islands, and subjecting these patterned samples to annealing was found to be more effective in reducing dislocations compared to the in-situ whole wafer annealing. However, subsequent growth of CdTe on the patterned and annealed samples to achieve thicker epilayers resulted rough surface, making them unsuitable for detector development.