Investigation of Photoexcitation Energy Impact on Electron Mobility in Single Crystalline CdTe.

Viktor Djurberg,Saman Majdi,Jan Isberg,Nattakarn Suntornwipat

doi:10.3390/ma14154202

Abstract

The exceptional electronic properties of cadmium telluride (CdTe) allow the material to be used in a wide range of high energy radiation detection applications. Understanding the mechanisms of local carrier scattering is of fundamental importance to understand the charge transport in the material. Here, we investigate the effect of photoexcitation on electron transport properties in chlorine doped single crystalline cadmium telluride (SC-CdTe:Cl). For this purpose time of flight measurements were performed on SC-CdTe:Cl in order to study the electron drift mobility in the low injection regime. Measurements were made at the temperature intervals of 80 to 300 K, for an applied electric field between 270 and 1600 V/cm and for wavelengths of 532, 355 and 213 nm. We have found that the electron drift mobility was affected by the excitation energy for temperatures below 200 K. In addition, the measurements revealed that it is possible to determine impurity and shallow trap concentration by this method. The method proves to be extremely sensitive in measuring very low impurity levels and in identifying dominant scattering mechanisms.

Highlights

Division for Electricity, Department of Electrical Engineering, Uppsala University, Citation: Djurberg, V.; Majdi, S.; Abstract: The exceptional electronic properties of cadmium telluride (CdTe) allow the material to be used in a wide range of high energy radiation detection applications
In CdTe:Cl, charge carrier mobility tends to be limited by defect scattering at low temperatures [8]; a low impurity concentration is important
We have measured the electron mobility for a wide range of temperatures and with three different photoexcitation energies in single crystalline cadmium telluride (SC-CdTe):Cl using a time of flight method

Summary

Introduction

We investigate the effect of photoexcitation on electron transport properties in chlorine doped single crystalline cadmium telluride (SC-CdTe:Cl). For this purpose time of flight measurements were performed on SC-CdTe:Cl in order to study the electron drift mobility in the low injection regime. In CdTe:Cl, charge carrier mobility tends to be limited by defect scattering at low temperatures [8]; a low impurity concentration is important. Hall effect measurements are used to investigate the mobility of charge carriers in semiconductors This technique cannot be applied in the case of insulating or high resistivity CdTe:Cl as it gives indistinct results due to mixed electron and hole conduction. Electron–hole pairs are created by αparticles [11,12], pulsed electron beams [13,14], pulsed x-rays [15], or a pulsed laser [16,17,18,19,20]

Methods

Results

Conclusion