Three-dimensional field-effect transistors with top-down and bottom-up nanowire-array channels

nanowire transistor;High-electron-mobility transistor (HEMT);Fin field effect transistor (finFET);vapor-liquid-solid;gallium oxide;Metal–oxide–semiconductor field-effect transistor (MOSFET);wrap-gate

Chabak, Kelson D

关键词: nanowire transistor;    High-electron-mobility transistor (HEMT);    Fin field effect transistor (finFET);    vapor-liquid-solid;    gallium oxide;    Metal–oxide–semiconductor field-effect transistor (MOSFET);    wrap-gate;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/95466/CHABAK-DISSERTATION-2016.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This dissertation research effort explores new transistor topologies using three-dimensional nanowire (NW)-array channels formed by both bottom-up and top-down synthesis.The bottom-up NW research centers on the Au-catalyzed planar GaAs NW assembly discovered at the University of Illinois Urbana-Champaign (UIUC).The top-down NW research approach involves plasma etching of an emerging wide-bandgap material, Gallium Oxide (Ga2O3), to make arrays of NW channels (or fins) for high-power electronics.Bottom-up AlGaAs/GaAs heterostructure core-shell planar NWs are demonstrated on a wafer scale with excellent yield.Their placement is determined by lithographically patterning an array of Au seeds on semi-insulating GaAs substrate.The GaAs NWs assemble by lateral epitaxy via a vapor-liquid-solid mechanism and align in parallel arrays as a result of the (100) GaAs crystal plane orientation; then, a thin-film AlGaAs layer conforms to the GaAs NWs to form AlGaAs/GaAs NW high-electron mobility channels.Radio frequency (RF) transistors are fabricated and show excellent dc and high-frequency performance.An fmax > 75 GHz with < 2 V supply voltage and ION/IOFF > 104 is measured which is superior compared to carbon-based nanoelectronics and “spin-on III-V NWs”.A comprehensive small-signal model is used to extract the contributing and limiting factors to the RF performance of AlGaAs/GaAs NW-array transistors and predict future performance.Finally, a process is developed to show that III-V NWs on sacrificial epitaxial templates can be transferred to arbitrary substrates.Top-down NWs were formed from Sn-doped Ga2O3 homoepitaxially grown on semi-insulating beta-phase Ga2O3 substrates by metal-organic vapor phase epitaxy.First, conventional planar transistors were fabricated from a sample set to characterize and understand the electrical performance as a function of Sn-doping and epitaxial channel thickness.Second, the high-critical field strength was evaluated to highlight the benefit of using Ga2O3 as a disruptive technology to GaN and SiC.Lastly, the planar transistor results feed into a design for a top-down NW-array transistor.The Ga2O3 NW-arrays were formed by BCl3 plasma etching.A new wrap-gate transistor demonstrates normally-off (enhancement-mode) operation with a high breakdown voltage exceeding 600 V which is superior to any transistor using a 3D channel.