Improved Electron Transport Properties of Ga1-xInxSb Quantum Well Channel Using Strained-Al0.40In0.60Sb/Al1-yInySb Stepped Buffer

Abstract

The using InSb as channel is one of the effective method in order to improve cutoff frequency ( $f_{\mathrm{T}}$ ) because of the smaller electron effective mass ( $m^{\ast}$ ) and then the higher electron mobility ( $\mu$ ). However, the smaller $m^{\ast}$ , in turn, leads to the lower electron sheet density ( $N_{\mathrm{S}}$ ) in the quantum well (QW) channel owing to the smaller electron density of states (DOS), which results in the poor current drivability. Recently, have studied the Ga 1-x In x Sb QW channel as an alternative to the InSb QW. In this work, we demonstrate the improved electron transport properties of the Ga 1-x In x Sb quantum well (QW) channel by using the strained-Al 0.40 In 0.60 Sb/Al 1-y In y Sb stepped buffer. The Ga 0.22 In 0.78 Sb QW channel with the strained-Al 0.40 In 0.60 Sb/Al 0.25 In 0.75 Sb stepped buffer exhibits electron mobility ( $\mu$ ) of 15,500 cm2/Vs, electron sheet density ( $N_{\mathrm{S}}$ ) of $2.05\times 10^{12}\text{cm}^{-2}$ , and sheet resistance ( $R_{\mathrm{S}}$ ) of $197 \Omega/\square$ . As compared with InSb HEMT, $\mu$ decreases to 87%, $N_{\mathrm{S}}$ increases to 193%, and $R_{\mathrm{S}}$ decreases to 59%. These results indicate the potential of the Ga 1-x In x Sb QW structures with the strained stepped buffer for ultra-low power and Terahertz applications.