Correlations between microscopic properties and the photorefractive response for vanadium-doped CdTe

Abstract

We present a summary of the experimental results, the attempts of interpretation at the present stage, and the conclusions of coupled investigations on semi-insulating, n-type and p-type vanadium-doped CdTe crystals. Combining electron paramagnetic resonance and magnetic circular dichroism permits the monitoring and the quantitative assessment of [ V 2ϩ ] and [ V 3ϩ ] defect concentrations. Photoabsorption results are presented and are discussed in terms of photoionization processes at various wavelengths. The temperature and the spectral dependence of the steady-state photoconductivity are carefully studied in the near infrared. The results are discussed in terms of electronic transitions for the two vanadium charge states. Finally, the photorefractive performances of the semi-insulating sample are analyzed in a two-beam-coupling experiment and are correlated to the properties of the V 2ϩ /V 3ϩ donor states to derive photoionization cross sections.

Energy structure and micromechanism of photo-EMF effect in adaptive IR-detectors based on CdTe:V crystals

“…The absorption band in the longwave region near 0.83 eV corresponds to the intracenter absorption between the 4 T 1 (F) and 4 A 2 (F) states of the V 2+ impurity ions [8]. The absorption band in the range 0.88-0.99 eV indicates existence of V 3+ centers in CdTe:V crystals [4]. The wide absorption band near 1.20 eV is due to both the intracenter transitions between the 4 T 1 (F) and 4 T 1 (P) states of the V 2+ impurity ions and their overlap with the photoionization absorption.…”

“…During last years ever increasing attention has been given to semiconductor crystals, among which cadmium telluride has the best characteristics for potential applications [1,2,3,4,5]. The production of above mentioned photorefractive materials requires growing of high optical quality semi-insulating crystals, which have deep donor impurity centers.…”

“…The production of above mentioned photorefractive materials requires growing of high optical quality semi-insulating crystals, which have deep donor impurity centers. It should be noted that the formation of deep impurity levels located near the middle of the band gap of those crystals appear as a result of their doping by the 3d-elements [4,5,6,7,8].…”

L'effet photoréfractif

“…Sans champ électrique appliqué il est optiquement isotrope. Le dopage au vanadium [175] est le plus utilisé et rend le CdTe sensible dans la gamme de longueurs d'onde de 1 à 1,5 um [176,177].…”

Photorefractive Properties of CdTe:Sn

“…Until now the photorefractive properties have been reported for vanadium-doped [5,6], titanium-doped [5], germanium-doped [7], iron-doped [8] and vanadium-manganese codoped [9] CdTe. At the same time it is known that tin forms a deep level in the forbidden band of CdTe [10] and therefore may improve the photorefractive response.…”