Determination of minority carrier lifetime and interface trap density in Ge MIS capacitors

Ultra thin high-k ZrO₂ films (14 nm) have been deposited on germanium at a low temperature (~150degC) using microwave plasma enhanced chemical vapor deposition (PECVD) technique. Several samples were NO-plasma nitrided before deposition of the high-k films to minimize the surface roughness and interdiffusion of germanium. Using Capacitance-time (C-t) technique the value of bulk generation lifetime from the slope of the Zerbst plot is found to be 11 mus for Ge. Conductance method, based on variable frequency C-V and G-V measurements, was used to compare the interface trap density D_it for ZrO₂/GeO₂/Ge and ZrO₂/GeO_xN_y/Ge MIS capacitors. The calculated doping concentration (NA) from high frequency C-V is calculated to be ~2times10¹⁵ cm^-3.