Surface recombination and space-charge-limited photocurrent-voltage (PC-V) measurements in (Cd,Mn)Te samples. Kinetics of photocurrent (PC)

TL;DR

This study investigates how surface treatment affects photocurrent-voltage measurements in (Cd,Mn)Te samples, revealing surface traps' influence on detector parameter estimation and emphasizing the importance of surface quality assessment.

Contribution

It demonstrates the impact of surface etching on PC-V characteristics and identifies shallow surface traps as a key factor affecting measurements in (Cd,Mn)Te detectors.

Findings

Surface etching introduces shallow traps affecting PC-V measurements.

Surface treatment significantly influences charge distribution and measurement accuracy.

Hole contribution to photoconductivity is minimal in PC kinetics.

Abstract

Photocurrent-voltage characteristic (PC-V) is a method of determining the critical parameter in X-ray and gamma-ray detector plates, i.e., the carrier mobility - lifetime product, mt. We show on the (Cd,Mn)Te samples that the measurement results depend strongly on the surface treatment and the charge space distribution. The PC-V characteristics obtained for hv > Eg and hv ~ Eg indicated that etching with 20% HCl caused an appearance of a significant concentration of very shallow surface traps at the (Cd,Mn)Te sample surface. These traps seriously changed the measurements of PC-V characteristics and PC kinetics. We also noticed a small contribution of holes to photoconductivity in the PC kinetics. The PC-V characteristics measurements for hv > Eg may test the detector plate surface quality.