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

Ultra thin high-k ZrO
₂
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 ZrO
₂
/GeO
₂
/Ge and ZrO
₂
/GeO
_x
N
_y
/Ge MIS capacitors. The calculated doping concentration (NA) from high frequency C-V is calculated to be ~2times10
¹⁵
cm
^-3
.