Mapping of inhomogeneous quasi-3D electrostatic field in electro-optic materials

Václav Dědič,Jan Franc,Tomáš Fridrišek,Martin Rejhon,Jan Kunc,Utpal N Roy,Ralph B James

doi:10.1038/s41598-021-81338-w

Abstract

This paper describes a new method for direct measurement and evaluation of the inhomogeneous electrostatic vector field with translational symmetry in electro-optic materials exhibiting the Pockels effect. It is based on the evaluation of maximum transmittance of low intensity light passing through a sample under a voltage bias. Here, the sample is located between rotating crossed polarizers, and camera images are obtained at each point to determine the electric field. The evaluation procedure is demonstrated using data acquired on a CdZnTeSe quasi-hemispheric semiconductor gamma-ray detector. In addition to CdTe-related compounds, the method can be used for various other materials showing overline{4}3m symmetry such as GaAs, CdTe, GaP, 3C-SiC, and ZnS. Furthermore, it can be generalized to other crystalline materials showing the Pockels effect. The method can be used to probe the space charge and the electric field in several kinds of electronic components and devices, as well as provide useful data on the role of defects, contact configurations and other surface and bulk inhomogeneities in the material that can affect the distribution of the internal electric field.

Highlights

This paper describes a new method for direct measurement and evaluation of the inhomogeneous electrostatic vector field with translational symmetry in electro-optic materials exhibiting the Pockels effect
We show a new approach to perform high spatial resolution mapping of the internal quasi-3D electrostatic vector field with inhomogeneous distribution in a material showing a Pockels effect for an arbitrary crystallographic orientation
An investigation of the electric field vector distribution measurement in quasi-hemispheric CdZnTeSe detectors is motivated by the need to understand the space charge accumulation in devices, which sometimes appears during semiconductor detector operation and can negatively affect detector performance

Summary

Introduction

This paper describes a new method for direct measurement and evaluation of the inhomogeneous electrostatic vector field with translational symmetry in electro-optic materials exhibiting the Pockels effect. We show a new approach to perform high spatial resolution mapping of the internal quasi-3D electrostatic vector field with inhomogeneous distribution in a material showing a Pockels effect for an arbitrary crystallographic orientation. This generalized method is based on the transmittance measurements of the illuminated crystal placed between two rotating orthogonal polarizers. CdZnTeSe material was chosen for this study, because it has recently emerged as a promising material for X- and gamma-ray detectors due to its relatively low Te inclusions, absence from sub-grain boundary networks, and better compositional homogeneity compared to C dZnTe24–26, plus the 1D Pockels effect has been much less used in this material

Methods

Results

Conclusion