Spectral Dependence of the Photoplastic Effect in CdZnTe and CdZnTeSe.

Jan Franc,Martin Rejhon,Miroslav Cieslar,Ralph B James,Roman Grill,Hassan Elhadidy,Vladimír Šíma,Utpal Roy,Maroš Bratko,Pavel Moravec,Václav Dědič

doi:10.3390/ma14061465

Jan Franc, Martin Rejhon + Show 9 more

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https://doi.org/10.3390/ma14061465

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Abstract

We studied the spectral dependence of the Vickers microhardness HV0.025 of CdZnTe and CdZnTeSe samples upon illumination and found out that it increases over the entire applied spectral range of 1540–750 nm. We also found out that the photoconductivity and microhardness are correlated. We observed changes in the correlation diagram (change of slope and an abrupt change of HV0.025 at several wavelengths of the illuminating light). Based on measurements of the relative changes of the space charge upon illumination using the Pockels effect, we suggest that the observed spectral dependence of positive photoplastic effect in CdZnTe and CdZnTeSe can be explained by the trapping of photoinduced electrons and holes, which affects the motion of the partial dislocations. The underlying physical explanation relies on the assumption that reconstructed bonds break before dislocation glide.

Highlights

CdTe and Cd1-x Znx Te (x = 0.1–0.2) are widely used II-VI semiconductors applied in solar cells [1], room-temperature X-ray and gamma-ray detectors [2], substrates for the narrow gap (HgCd)Te epitaxial infrared detectors [3], electro-optical modulators and other optical applications [4]
The photoplastic effect (PPE) has been extensively studied in AIIBVI semiconductors where generally a positive PPE has been reported
The PPE of CdTe was studied in [10,11], and a positive PPE was found to be more pronounced in low resistivity samples

Summary

Introduction

The mobility of the dislocations is reduced as a result of the modification of the distribution of the electric charge along the dislocation lines when compared to the situation without illumination. This results in the experimentally observed positive PPE. The DFT calculations [20] show that the cores of several types of dislocation in CdTe may undergo lattice reconstructions along the dislocation lines accompanied with charge modulations resulting in the transformation of the originally metallic character to the semiconducting character of the reconstructed cores

Materials and Methods

Results

Evolution

Correlation