Effects of a a-Si:H layer on reducing the dark current of 1310nm metal–germanium–metal photodetectors

Two approaches of hydrogenated-amorphous-silicon (a-Si:H), as Schottky-barrier height (SBH) enhancement and passivation layers, were investigated to suppress dark current of 1310nm metal–germanium–metal photodetectors (MGM-PDs). Observations show that when a-Si:H is inserted between metal and Ge, th...

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Bibliographic Details
Published in:Thin solid films 2011-03, Vol.519 (11), p.3819-3821
Main Authors: Hwang, J.D., Zhang, E.H.
Format: Article
Language:English
Subjects:
a-Si:H
Dark current
Defects
Germanium
Passivation
Photocurrent
Photodetectors
Photoelectric effect
Responsivity
Schottky-barrier height
Thin films
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Summary:Two approaches of hydrogenated-amorphous-silicon (a-Si:H), as Schottky-barrier height (SBH) enhancement and passivation layers, were investigated to suppress dark current of 1310nm metal–germanium–metal photodetectors (MGM-PDs). Observations show that when a-Si:H is inserted between metal and Ge, the dark current is effectively reduced due to SBH enhancement, but similarly lowers photocurrent resulting from the blocking of a-Si:H. In contrast with a-Si:H acting as a passivation layer a very high photo-to-dark current ratio of 6530 is achieved with a high responsivity of 0.72A/W, attributing to the defect centers on the Ge surface which are passivated. Such a result suggests that the a-Si:H passivation layer is a good candidate in fabricating high-quality 1310nm MGM-PDs.
ISSN:0040-6090
1879-2731
DOI:10.1016/j.tsf.2011.01.232