COULOMB ENERGY OF TRAPS IN SEMICONDUCTOR SPACE-CHARGE REGIONS

Large Coulomb barriers exceeding DELTAE almost-equal-to 250 meV are estimated and emission rates of trap centers in semiconductor space-charge regions Depending on the charge state of the trap, the capture rate or both the capture arid emission rates are activated or deactivated, respectively. The Coulomb energy raises the equilibrium energy state of a trap center that is repulsively charged when occupied. Quantitative agreement of the calculated Coulomb energy is obtained with trapping rates for single individual interface traps in metal-oxide-semiconductor (MOS) structures measured by random telegraph signals. The Coulomb barrier is reduced in MOS capacitors by partial screening due to mobile charge carriers in the inversion channel. The Coulomb energy can be externally controlled in MOS structures by the gate bias voltage.