Photoresponses in polycrystalline silicon phototransistors incorporating germanium quantum dots in the gate dielectrics

Tseng, S. S.; Chen, I. H.; Li, P. W.
November 2008
Applied Physics Letters;11/10/2008, Vol. 93 Issue 19, p191112
Academic Journal
Polycrystalline silicon (poly-Si) thin-film transistors (TFTs) incorporating germanium (Ge) quantum dots (QDs) in the gate oxide were fabricated as efficient blue to near ultraviolet phototransistors for light detection and amplification. Under 405–450 nm light illumination, Ge QDs poly-Si TFTs exhibit not only strong photoresponses in the drive current but also much improved subthreshold characteristics than that measured in darkness. This originates from the fact that only photoexcited holes within Ge QDs are injected into the active channel via vertical electric field and contribute excess mobile carriers for photocurrent but without the associated photogenerated electron induced junction barrier lowering.


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