Electron Mobility in Surface- and Buried-Channel Flatband $\hbox{In}_{0.53}\hbox{Ga}_{0.47}\hbox{As}$ MOSFETs With ALD $\hbox{Al}_{2}\hbox{O}_{3}$ Gate Dielectric

Abstract

In this letter, we investigate the scaling potential of flatband III-V MOSFETs by comparing the mobility of surface and buried-channel In0.53Ga0.47As devices employing an atomic layer-deposited Al2O3 gate dielectric and a delta-doped InGaAs/InAlAs/InP heterostructure. Peak electron mobilities of 4300 cm2/V · s and 6600 cm2/V · s at a carrier density of 3 × 1012 cm-2 were determined for the surfaceand buried-channel structures, respectively. In contrast to similarly scaled inversion-channel devices, we find that the mobility in surface channel flatband structures does not drop rapidly with the electron density, but rather high mobility is maintained up to carrier concentrations around 4 × 1012 cm-2 before slowly dropping to around 2000 cm2/V · s at 1 × 1013 cm-2. We believe these to be world leading metrics for this material system and an important development in informing the III-V MOSFET device architecture selection process for the future low-power highly scaled CMOS.