Electrical properties of the stacked ZnS/photo-enhanced native oxide passivation for long wavelength HgCdTe photodiodes
- National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Electrical Engineering
- Chung Shan Inst. of Science and Technology, Lung-Tan (Taiwan, Province of China)
HgCdTe is a suitable material for infrared (IR) detector applications in the two atmospheric spectra`s window, (i.e., 3--5 {micro}m and 8--12 {micro}m). Unlike other IR materials such as InSb, one can easily change the composition ratio between Hg and Cd to adjust the bandgap energy of HgCdTe and thus to adjust the corresponding wavelength. Also, because of its intrinsic property, HgCdTe photo detector has a long carrier life time and a small thermal generation rate that is important for high temperature operation. A new surface treatment method, i.e., stacked ZnS/photo-enhanced native oxide, is proposed for HgCdTe passivation. The photo native oxide layer was deposited by direct photo chemical vapor deposition (DPCVD) using a deuterium (D{sub 2}) lamp as the optical source. By using this method, they found that there is no accumulation of Hg in the oxide/HgCdTe interface regions. Since the photo chemical vapor native oxidation is a dry oxidation method deposited at a low temperature, it can effectively suppress the Hg enhancement and the Cd depletion effects and thus obtain a high quality interface. The electrical properties of a Au-ZnS/photo-enhanced native oxide/HgCdTe metal-insulator-semiconductor (MIS) diodes were characterized by capacitance-voltage (C-V) measurement. It was found that the flat band voltage of such a MIS diode is close to 0.2 V with an effective fixed oxide charge lower than 1 {times} 10{sup 10} cm{sup {minus}2}.
- OSTI ID:
- 253683
- Journal Information:
- IEEE Photonics Technology Letters, Journal Name: IEEE Photonics Technology Letters Journal Issue: 5 Vol. 8; ISSN 1041-1135; ISSN IPTLEL
- Country of Publication:
- United States
- Language:
- English
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