本論文為利用砷化銦材料優異的高電子遷移率及優異電子飽和速度特性，發展低功率和高速的異質接面場效電晶體(HFET)。由於銻化物材料系統的化學穩定性並不好，在元件製作時容易引起磊晶材料衰化，因此我們將藉著改善磊晶材料的品質和發展鈍化製程，防止元件電性的衰化，最佳化其直流及高頻特性。 我們利用快速熱退火製程將歐姆接觸電阻降低至RC=0.06Ω-mm。閘極長度2μm的元件特性於汲極偏壓VDS=0.4V下，其汲極飽和電流為IDSS=650mA/mm及轉導增益為gm=1,223mS/mm，電流增益截止頻率與閘極長度乘積比高達fT×Lg=68GHz-μm。另外利用鈍化製程降低缺陷能態密度，在脈波電流-電壓量測分析中，以一階段鈍化元件的表面缺陷最不顯著，且具有低閘極漏電流特性和改善次臨限行為的Ion/Ioff =3831和S.S.=111mV/dec，元件的良率從5%提升至95%。最後，我們利用一階段鈍化製程，製作0.5μm的T型閘極元件，證明fT=93GHz和fmax=82GHz之高頻性能。This thesis develops low-power and high-speed heterpjunction field-effect transistors using InAs channels which have very high electron mobility and excellent peak velocity. Due to chemical instability of lattice-matched antimonides which easily degrade epitaxial materials, improvements of epitaxial quality and developments of passivation processes are performed to alleviate its effects on dc and rf performances. Ohmic contacts are reduced as low as 0.06Ω-mm utilizing a rapid thermal annealing process. In a 2μm-gate-length device, drain current is 650mA/mm and transcondutance is 1,223mS/mm at VDS=0.4V. A product of cut-off frequency and gate length as high as 68 GHz-μm is achieved. In addition, an optimized passivation process is successfully developed to decrease trap density. In a pulsed I-V measurement, the charge trapping in a one-step passivated device is least pronounced and improved subthreshold characteristics of Ion/Ioff =3831 and S.S.=111mV/dec are demonstrated. Device yield is raised from 5% to 95%. Finally, a HEMT of a 0.5μm e-beaming writing T-gate shows excellent rf performance of fT=93GHz and fmax=82GHz using the developed one-step passivation approach.
