| After about fifty years of development in silicon metal-oxide-semiconductor field-effect transistor (MOSFET), it has become more and more difficult to continue transistor scaling due to the limitations in lithography, power consumption, and reliability. Recently, great effort has been put into searching for alternative channel structures or materials for future high-performance and low-power logic applications. Considerable progress has been made in the research of several novel devices, such as carbon-nanotube (CNT) field-effect transistors (FETs), silicon nanowire FETs, graphene FETs, and planar FETs with alternative channel materials such as Ge, InAs, InSb, and InGaAs. This dissertation discusses the electrical characterization of the interface traps, analysis of the inversion charge, electron mobility and junction leakage current of Al2O 3/InxGa1- xAs (x = 0.53, 0.65 or 0.75) MOSFETs.;Charge pumping has been used to characterize the interface traps between Al2O3 and InGaAs in n-channel inversion-mode MOSFETs. An analysis of the charge pumping current with gate voltage pulses of different rise and fall times has enabled the interface trap density to be extracted across the energy bandgap, with an average value between the mid 10 12 and low 1013 cm-2eV -1. The majority of interface traps in indium-rich InGaAs metal-insulator-semiconductor structures have been identified as donors, which limits the off-state performance of InGaAs MOSFETs such as subthreshold slope, drain-induced barrier lowering, and on/off current ratio. The results obtained in our measurements help explain the promising on-state performance of the Al2O3/InGaAs MOSFETs and the need to further improve the interface so that its off-state performance can be on par with that of the Si MOSFET.;The electron mobility in Al2O3/InGaAs MOSFETs has been analyzed for scattering by oxide charge as well as interface charge and roughness, and compared with measured transfer characteristics from depletion to inversion. The analysis shows that in strong inversion the electron mobility can be as high as ∼3000 cm2/V/s and is mainly limited by interface roughness. The extracted interface roughness from the measured data is two to seven times that of the interface between a high-kappa dielectric and Si, assuming the correlation lengths are comparable. Therefore, to fully benefit from the high bulk mobility of InGaAs, its interface roughness with the gate oxide needs to be further improved.;Finally, the reverse junction leakage current has been analyzed by calculating diffusion, generation, and tunneling currents, and compared with measurement at room temperature. We find that the leakage current increases with In mole fraction. Generation and tunneling currents dominate in medium- and high-bias regions, respectively. |
