Impact of Fermi level pinning inside conduction band on electron mobility in InGaAs metal-oxide-semiconductor field-effect transistors

Abstract

Combining the split capacitance-voltage method with Hall measurements revealed the existence of interface traps within the conduction band (CB) of InGaAs in metal-oxide-semiconductor (MOS) structures with Al2O3 (or HfO2)/InGaAs interfaces. The impact of these interface traps on inversion-layer mobilities in InGaAs MOS field-effect transistors with various interface structures was investigated. We found that the interface traps (>1013 cm−2 eV−1) induce Fermi level pining at an energy level 0.21–0.35 eV above the CB minimum, which degrades the mobilities in the high inversion carrier concentration region. Furthermore, the energy levels are tunable by changing the interface structures.