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We have fabricated dual gate field effect transistors (FETs) with 12 nm-thin black phosphorus (BP) channel on glass substrate, where our BP FETs have a patterned-gate architecture with 30 nm-thick Al2O3 dielectrics on top and bottom of a BP channel. Top gate dielectric has simultaneously been used as device encapsulation layer, controlling the threshold voltage of FETs as well when FETs mainly operate under bottom gate bias. Bottom, top, and dual gate-controlling mobilities were estimated to be 277, 92, and 213 cm(2)/V s, respectively. Maximum ON-current was measured to be ∼5 μA at a drain voltage of -0.1 V but to be as high as ∼50 μA at -1 V, while ON/OFF current ratio appeared to be 3.6 × 10(3) V. As a result, our dual gate BP FETs demonstrate organic light emitting diode (OLED) switching for green and blue OLEDs, also demonstrating NOR logic functions by separately using top- and bottom-input.

We report on the fabrication of top-gate phototransistors based on a few-layered MoS2 nanosheet with a transparent gate electrode. Our devices with triple MoS2 layers exhibited excellent photodetection capabilities for red light, while those with single- and double-layers turned out to be quite useful for green light detection. The varied functionalities are attributed to energy gap modulation by the number of MoS2 layers. The photoelectric probing on working transistors with the nanosheets demonstrates that single-layer MoS2 has a significant energy bandgap of 1.8 eV, while those of double- and triple-layer MoS2 reduce to 1.65 and 1.35 eV, respectively.

We report on the fabrication of top-gate phototransistors based on a few-layered MoS(2) nanosheet with a transparent gate electrode. Our devices with triple MoS(2) layers exhibited excellent photodetection capabilities for red light, while those with single- and double-layers turned out to be quite useful for green light detection. The varied functionalities are attributed to energy gap modulation by the number of MoS(2) layers. The photoelectric probing on working transistors with the nanosheets demonstrates that single-layer MoS(2) has a significant energy bandgap of 1.8 eV, while those of double- and triple-layer MoS(2) reduce to 1.65 and 1.35 eV, respectively.