Comprehensive Review on CdTe crystals: Growth, Properties, and Photovoltaic Application

Year 2022, Volume: 2 Issue: 2, 180 - 196, 31.10.2022

Bibin John S. Varadharajaperumal

https://doi.org/10.5152/tepes.2022.22016

https://izlik.org/JA87GK64FD

Abstract

Despite the deep interest of materials scientists in cadmium telluride (CdTe) crystal growth, there is no single source to which researchers can turn for com- prehensive knowledge of CdTe compound semiconductor synthesis protocols, physical characteristics, and material performance. Considering this, the present review work focuses on bridging these shortcomings. The CdTe crystals with direct band gap (Eg) have been in limelight in the photovoltaic application (PV) as the optoelectronic properties such as E (1.49 eV), absorption coefficient (~105 cm−1), p-type conductivity, carrier concentration (6 × 1016 cm−3), and appreciably high mobility (1040 cm2/V s) at the room temperature are reported, which are optimum for solar cells. Additionally, Cd-based crystals have also been widely studied and implemented in the field of α and γ-ray radiation detectors because of their extraordinary advantages like a large atomic number, low weight, high mechanical as well as thermal stability, flexibility, and the availability of the constituent materials. Cadmium telluride has demerits like toxicity (ecological dam- age) and high chances for defects/dislocations due to high thermal conductivity at melting temperature and high melting temperature, which will complicate the growth of stoichiometric CdTe crystals at high temperatures. Even though CdTe has the aforementioned issues, on the other hand, the absorber material reached a milestone (solar cell efficiency in the order of 22%), which enhances the attractiveness of this binary compound more and more in the field of crys- tal growth technology. In this regard, the review work focused on the periodic evolution of the growth protocols until now for the production of bulk, good quality CdTe crystals. The different synthesis methods, characterization, and recent progress in the field of crystalline CdTe were discussed briefly. Important physicochemical characteristics are presented in the tables and remaining issues due to chemical in-homogeneity, defects, imperfections, etc., have been discussed, which could facilitate the researchers who are working on this class of compound semiconductors. The applications of CdTe crystals to PV fields are also discussed separately in this review paper.

Keywords

Cadmium telluride (CdTe) , traveling heater method , horizontal traveling heater method , sublimation method , dislocation density , photovoltaic application

Thanks

The authors is grateful to Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, Karnataka, India for the support and encouragement towards my research. The authors would also extent the thank to Prof. Peter Rudolf (former Editor of Journal of Crystal Growth) for his detailed explanations of diverse type’s crystal growth techniques for CdTe single crystal during the program “Indian Summer School on Crystal Growth (ISSCG-2020)”.

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