• Wahab, Yasmin Abdul
• Chowdhury, Zaira Zaman
• Soin, Norhayati Binti
• Hatta, S. F. W. Muhamad
• Mohafez, Hamidreza
• Misran, Halina
• Nur-E-Alam, Mohammad

Abstract

<jats:title>Abstract</jats:title><jats:p>The thermal treatment of the CdTe thin film in the presence of CdCl<jats:sub>2</jats:sub> is a crucial step in the creation of high-efficiency CdTe-based solar cells. The process influences the grain growth, grain boundary passivation, and doping, including CdTe recrystallization, and promotes to building of the photovoltaic junction. However, toxic Cd<jats:sub>2</jats:sub><jats:sup>+</jats:sup> ions released by the CdCl<jats:sub>2</jats:sub>, which is highly soluble in water is a major environmental concern of this process. Also, the price of CdCl<jats:sub>2</jats:sub> (about 30 cents/gram) that drives up manufacturing costs is another limitation of the current processs. Finding a non-toxic Cl molecule is therefore currently in high demand and key factor for the thermal treatment of CdTe. In this study, MgCl<jats:sub>2</jats:sub> was thoroughly explored as an alternative, non-toxic, and somewhat less expensive chlorine-containing chemical for CdTe thermal treatment. CdTe thin films, approximately 1.0 µm thick, were deposited on a glass substrate at 350 ºC using RF magnetron sputtering, and after deposition, different concentrations of MgCl<jats:sub>2</jats:sub> (0.2 M, 0.3 M, 0.4 M, and 0.5 M) mixed with 10% methanol were applied to the films for around 10 s, forming a thin MgCl<jats:sub>2</jats:sub> coating, followed by the optimized heat treatment at 400 ºC in a nitrogen–oxygen environment. We found that the thermal treatment of CdTe films using MgCl<jats:sub>2</jats:sub> showed improved crystallinity, surface morphology, impurity profiles, and carrier density similar to the conventional CdCl<jats:sub>2</jats:sub> process. The sample treated with 0.4 M MgCl<jats:sub>2</jats:sub> exhibited the best output as obtained the band gap of nearly 1.46 eV, a refractive index of 2.84, a carrier concentration of 9.81E+15 cm<jats:sup>−3</jats:sup>, and mobility 35.08 cm<jats:sup>2</jats:sup>/V-S with a moderate resistivity. Our findings show that MgCl<jats:sub>2</jats:sub> could be utilized instead of traditional CdCl<jats:sub>2</jats:sub> in the current fabrication procedure, which substantially lowers the environmental hazard with a cost-effective production process of CdTe-assembled solar cells.</jats:p>

Topics

• Deposition
• density
• impedance spectroscopy
• surface
• grain
• resistivity
• mobility
• grain boundary
• thin film
• Oxygen
• glass
• glass
• laser emission spectroscopy
• Nitrogen
• forming
• recrystallization
• crystallinity
• grain growth