Atomic-Layer-Deposited Al2O3 as Top-Gate Dielectric

Abstract—We demonstrate atomic-layer-deposited (ALD) high-k dielectric integration on 2-D layer-structured molybdenum disulfide (MoS2) crystals and MoS2 dual-gate n-channel MOSFETs with ALD Al2O3 as the gate dielectric. Our C–V study of MOSFET structures shows good interface between 2-D MoS2 crystal and ALD Al2O3. Maximum drain currents using back gates and top gates are measured to be 7.07 and 6.42 mA/mm, respectively, at Vds = 2 V with a channel width of 3 µm, a channel length of 9 µm, and a top-gate length of 3 µm. We achieve the highest field-effect mobility of electrons using back-gate control to be 517 cm2/V · s. The highest current on/off ratio is over 108. Index Terms—Atomic layer deposition, MOSFET, MoS2. I