An InAs/high-k/low-k structure: Electron transport and interface analysis

We fabricated and investigated an InAs/high-k/low-k structure in comparison with an InAs/low-k structure, where the former and the latter are respectively obtained by bonding of InAs/Al2O3/AlN and InAs on low-k flexible substrates (FS). The InAs/high-k/low-k (InAs/Al2O3/AlN/FS) exhibits electron mobilities immune to interface fluctuation scattering, whereas this scattering is serious for the InAs/low-k (InAs/FS). Moreover, we find that electron sheet concentrations in the InAs/high-k/low-k are significantly higher than those in the InAs/low-k. From InAs/Al2O3 interface analysis by energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy, we find that the higher electron concentrations can be attributed to natural modulation doping from Al2O3 to InAs.