Photoresponses in Poly-Si Phototransistors Incorporating Germanium Quantum Dots in the Gate Dielectrics

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. The drain current measured under 405 nm light irradiation of 25 muW improves ~45% as compared to that measured in darkness at V_GS=-3 V. The poly-Si TFTs exhibited strong photoresponses in drive current under 405~450 nm light illumination, resulting from photoexcited holes in Ge QDs flow into the channel layer of the transistor via the gate bias to increase the channel mobile carriers.