CdTe films deposited by helicon sputtering for p-type Hg0.77Cd0.23Te surface passivation

摘要

Abstract: We investigated the passivation properties of CdTe films that were deposited on p-type Hg$-0.77$/Cd$-0.23$/Te using the helicon sputtering method. Crystallinity and morphological microstructure of the CdTe films were determined by transmission electron microcopy and atomic force microscopy, respectively. We found that the CdTe films are polycrystalline and provide good morphological properties: they have no granular-type defects and no pin-holes. Electrical measurements of metal-insulator semiconductor devices showed that the properties of the CdTe/HgCdTe interface mainly depend on deposition pressure and the conditions of post-deposition annealings. It was observed that CdTe deposition at higher pressure reduces the surface deposition damage that is responsible for increasing the positive fixed charges, the slow traps and other degradations of the HgCdTe surface. Moreover, post-deposition annealing at a temperature above 100 degrees Celsius improves the thermal stability of the electrical properties of the interface. A gate-controlled diode that was produced with post-deposition annealing showed that CdTe films deposited by helicon sputtering were essentially suitable for passivation of HgCdTe photodiode arrays. !5