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

摘要

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 Al_2O_3 (or HfO_2)/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 (＞10~(13)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.