Microstructure of CdTe thin films after mixed nitric and phosphoric acids etching and (HgTe, CuTe)-graphite pasting

We report on our investigation of the microstructure and composition of the surface of CdTe films after mixed nitric and phosphoric (NP) acids etching, (HgTe, CuTe)-graphite pasting, and thermal annealing. We find that after this process, a thin layer of CdxHg1−xTe forms between the CdTe and Te-rich layers, giving a structure of CdTe/CdxHg1−xTe/Te. High-resolution electron microscopy reveals that the CdxHg1−xTe layer has an epitaxial relationship with the CdTe. Bromine/methanol-etched samples or samples with intentionally deposited Te layers do not form the CdxHg1−xTe layer after (HgTe, CuTe)-graphite pasting and thermal annealing, indicating that they cannot act as fully as the NP etching.