Steady-state photoconductivity of gallium- and indium-doped hydrogenated amorphous germanium thin films
The effects of gallium and indium p-type doping on the photoconductivity of hydrogenated amorphous germanium (a-Ge:H) thin films deposited by the rf-sputtering method are reported. The quantum efficiency-mobility-lifetime (ημτ) product was determined at room temperature as a function of the dark Fer...
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Veröffentlicht in: | Journal of applied physics 1998-01, Vol.83 (1), p.353-357 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The effects of gallium and indium p-type doping on the photoconductivity of hydrogenated amorphous germanium (a-Ge:H) thin films deposited by the rf-sputtering method are reported. The quantum efficiency-mobility-lifetime (ημτ) product was determined at room temperature as a function of the dark Fermi energy EF on samples with a relative dopant concentration range between ≈3×10−5 and ≈10−2. A decrease of ημτ is observed with the increase of the Ga concentration until a minimum is reached for compensated samples (EF close to midgap level), where ημτ is about 16 times lower than the value obtained for intrinsic samples. This behavior is followed by an ημτ increase as EF crosses the midgap level. Then, for higher Ga doping levels, ημτ decreases again. For In-doped samples, on the other hand, a monotonic decrease of ημτ is measured for all the impurity concentration range. These results are consistent with a model which assumes that the dangling bond is the main recombination path, and give independent evidence for the lack of correlation between the defect density and EF in p-type doped a-Ge:H. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.366689 |