Diameter-Dependent Internal Gain in Ohmic Ge Nanowire Photodetectors
- 26 April 2010
- journal article
- Published by American Chemical Society (ACS) in Nano Letters
- Vol. 10 (6), 2043-2048
- https://doi.org/10.1021/nl100136b
Abstract
We report a diameter-dependent photoconduction gain in intrinsic Ge nanowire (NW) photodetectors. By employing a scanning photocurrent imaging technique, we provide evidence that the photocarrier transport is governed by the hole drift along the Ge NWs, ensuing the higher internal gain up to ∼103 from the thin NWs. It is found that the magnitudes of both gain and photoconductivity are inversely proportional to the NW diameter ranging from 50 to 300 nm. We attribute our observations to the variation in the effective hole carrier density upon varying diameters of Ge NWs, as a result of field effects from the diameter-dependent population of the surface-trapped electrons, along with a model calculation. Our observations represent inherent size effects of internal gain in semiconductor NWs, thereby provide a new insight into nano-optoelectronics.Keywords
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