Dependence of electron mobility on gate voltage sweeping width and deposition temperature in MOSFETs with HfO sub(2)/Al sub(2) O sub(3)/InGaAs gate stacks

In this study, we fabricated MOSFETs with Al sub(2) O sub(3)/InGaAs or HfO sub(2)/Al sub(2) O sub(3)/InGaAs gate stacks. The surface was subjected to nitrogen plasma and trimethylaluminum cleaning prior to low-temperature atomic layer deposition. Electron mobility was extracted using the capacitance-gate voltage (C-V sub(G)) and drain current-gate voltage (I sub(D)-V sub(G)) characteristics. We determined that the mobility decreased when the gate voltage sweeping width increased during C-V sub(G) and I sub(D)-V sub(G) measurements. In addition, we determined that the lowering of the deposition temperature to 120 [degrees]C improved the mobility of MOSFETs with HfO sub(2)/Al sub(2) O sub(3)/InGaAs gate stacks as compared with that corresponding to deposition at 300 [degrees]C. Furthermore, HfO sub(2)/Al sub(2) O sub(3)/InGaAs gate stacks with various Al sub(2) O sub(3) thicknesses were fabricated. When the number of Al sub(2) O sub(3) deposition cycles was more than 4, the mobility of MOSFETs with HfO sub(2)/Al sub(2) O sub(3)/InGaAs gate stacks improved, reaching the value of the Al sub(2) O sub(3)/InGaAs gate stack.