The Role of Oxide Traps Aligned with the Semiconductor Energy Gap in MOS Systems

This work demonstrates that when inelastic tunneling between oxide traps and semiconductor bands is considered, the traps with energy aligned to the semiconductor bandgap play a significant role in the frequency dispersion of the capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of metal-oxide-semiconductor (MOS) systems. The work also highlights that a nonlocal model for tunneling into interface states is mandatory to reproduce experiments when carrier quantization in the inversion layer is accounted for. A model, including these ingredients, is used to evaluate the energy and depth distribution of oxide traps in a n-In0.53Ga0.47As/Al2O3 MOS system and is able to accurately fit the C-V frequency dispersion from depletion to weak inversion. The oxide trap distribution determined from the C-V response predicts the corresponding G-V dispersion with frequency.