Study of Atomic Layer Deposition Al2O3/InGaAs, InAs Interfaces for MOSFET Application
|關鍵字:||金氧半電晶體;原子層;沉積氧化鋁;砷化銦鎵;砷化銦;Atomic Layer Deposition;Al2O3/InGaAs;Interfaces;MOSFET|
Al2O3/InAs MOSCAPs的電性指出對於改善Al2O3/InAs介面品質HCl加上TMA比起sulfide加上TMA是更有效果的。這個結果是由以下實驗觀察所得：ALD Al2O3 薄膜在200。C下沉積。300。C下沉積ALD Al2O3 薄膜再次驗證。同時本研究模擬Al2O3/InAs結構在低頻的C-V。結果顯示界面缺陷密度（Dit）分佈表現出 U 形在最小的Dit分佈位於InAs傳導帶最低處,i.e. 類施體陷阱在此能隙裡支配。這些類施體陷阱會顯著的減少藉由使用濕式化學溶液製程加上TMA預先處理。
藉由使用濕式化學溶液製程加上TMA預先處理和在純氫氣裡沉積後退火，對於Al2O3/In0.53Ga0.47As 界面品質有顯著提昇。使用ex-situ方法，強力的 C-V反轉行為第一次被觀察到在Al2O3/In0.53Ga0.47As MOSCAP。低Dit分佈可藉由模擬觀察到，同時模擬及電導法可確認最小Dit值 ~1011 eV-1cm-2。
This dissertation concentrates on the study of the reduction of InGaAs and InAs native oxides by using several kinds of surface treatments and gas annealing conditions to improve the atomic layer deposition (ALD) Al2O3/InGaAs, Al2O3/InAs interfaces qualities. Effects of trimethyl aluminum (TMA) treatment, wet chemical surface treatments, and a combination of these two kinds of treatments are investigated. The use of dry TMA treatment for the reduction of InGaAs, InAs native oxides at surface was only effective in the first pulse and then it became effectless. The study shows that the native oxides could be significantly removed by using wet chemical solution treatments such as HCl or sulfide. However, the combination of wet chemical solution treatments plus TMA pretreatment is the most effective way for InGaAs, InAs surface treatment. Electrical characterization of Al2O3/InAs MOSCAPs showed that the HCl plus TMA treatment was more effective in the improvement of Al2O3/InAs interface quality than that of sulfide plus TMA treatment. This conclusion was observed for the samples which were deposited with ALD Al2O3 films at 200oC and was confirmed again for the samples deposited with ALD Al2O3 films at 300oC. Low-frequency C-V simulations were performed for the Al2O3/InAs structures and the extracted interface traps density Dit profiles present a U-shape with the minimum of the Dit profiles located around the InAs conduction band minimum, i.e. donor-like traps dominates inside the bandgap. These donor-like traps were significant reduced by using wet chemical plus TMA treatments. By using the chemical solution plus TMA treatment along with post deposition annealing in pure H2 gas, a significant improvement of Al2O3/In0.53Ga0.47As interface quality was obtained. A strong C-V inversion behavior was first time observed in Al2O3/In0.53Ga0.47As MOSCAP by using an ex-situ method. Low Dit profile extracted by simulation was observed and the minimum Dit value of ~1011 eV-1cm-2 was confirmed by both simulation and conductance method. The electrical characteristics of Al2O3/InGaAs, InAs not only depend on the surface treatment methods but also depend on the properties of semiconductors themselves. The effect of semiconductor parameters such as bandgap, electron mobility, and intrinsic concentration on the C-V, I-V characteristics of Al2O3/InGaAs structures are discussed.
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