Charge trapping and detrapping in HfO2 high-κ MOS capacitors using internal photoemission

The focus of this paper is charge trapping within HfO2 high-κ metal-oxide-semiconductor capacitors. Charge was injected by constant voltage stress and internal photoemission. Capacitance-voltage and photocurrent-voltage measurements were taken in order to determine the centroid of oxide charge within the high-κ gate stack. Shifts in photocurrent response of the Al/HfO2/SiO2/p-type Si capacitors place the centroid within the HfO2 dielectric, near the Al gate. Large flatband voltage and photocurrent shifts were measured which indicates a large density of traps within these films. Measurements and observations support the result that it is the bulk traps within the HfO2 which contribute to charge trapping.