[[alternative]]Optical and electrical characterizations of the AlGaAs/InGaAs pseudomorphic and InAlAs/InGaAsSb metamorphic high electron mobility transistor structures

碩士電子工程學系[[abstract]]本論文利用變溫之光激發螢光光譜(PL)、霍爾量測(Hall measurement)探討砷化銦鋁/銻砷化銦鎵變晶式(樣品A)及砷化鋁鎵/砷化銦鎵假晶性(樣品B)高電子移動率電晶體之二維電子氣(2DEG)特性。樣品是以化學有機金屬氣相沈積(MOCVD)成長於砷化鎵基板上。從樣品A的光激發光光譜可以觀察到兩個躍遷訊號，將其定義為11H及31H。利用光激發光譜線之線型擬合獲得其量化能階的資訊，而套入理論公式後可估算其載子濃度。至於其霍爾量測，重摻雜覆蓋層導致的平行傳導效應嚴重影響其量測得到之載子濃度。然而，重摻雜層的存在與否卻對光激發光光譜沒有影響。此外，我們針對樣品設計了Hall bar之光罩，並導入製程，以漂移速度及閘極偏壓霍爾量測分析其通道內載子之傳輸。[[abstract]]We present the studies of two-dimensional electron gas (2DEG) on both InAlAs/InGaAsSb/InAlAs metamorphic high electron mobility transistor (mHEMT) and AlGaAs/InGaAs/AlGaAs pseudomorphic high electron mobility transistor (pHEMT) structures using temperature-dependent photoluminescence (PL) and Hall measurements. These two samples were grown by metal-organic chemical vapor deposition (MOCVD) on GaAs substrate and were designated as A(mHEMT) and B(pHMET). In the PL spectra of sample A, two optical features identified as 11H and 31H were observed. We extracted the quantitative energy information through fitting a phenomenological line-shape model to the PL spectra and estimated the carrier concentration using theoretical calculation. In Hall measurements, a parallel conducting problem occurs in heavily doped cap structure, which significantly affects the result of carrier concentration. However, the existence of heavily doped cap layer do not affect its PL spectra. Furthermore, Hall bar geometry was fabricated to characterize electron transport on sample B using drift-velocity and gated Hall measurements