fig7

Figure 7. XPS spectra of the CdTe single crystal at different ingot positions. (A) Survey spectra. (B) Cd 3d spin-orbit doublets. (C) Te 3d spin-orbit doublets. A small amount of Te⁴⁺ chemical state is observed on the surface of crystals. The binding energies of Cd 3d and Te 3d confirm that they correspond to the chemical states of Cd and Te in CdTe. The Cd: Te atomic ratios at the top, middle, and tail of the ingot are 0.9875:1, 1.0552:1, and 1.0048:1, respectively.