Dependence of Microstructure of Thermally Evaporated CuI Films on the Flow Rate of Argon Gas.

Semiconductor heterostructures are the core of various advanced electronic devices. Herein, the successful fabrication of CuI films has been reported using the thermal evaporation (TE) method. With the help of the TE technique, copper iodide (CuI) was grown over Si substrates to form CuI-based heterostructures. CuI has p-type semiconductor properties, which can be a potential candidate for future optoelectronic devices. The CuI/Si heterostructures have been fabricated at argon (Ar) gas flow rates of 25, 50, 75, and 100 sccm, respectively. The structural, compositional, morphological, electrical, and optical properties were investigated. According to x-ray diffraction (XRD) results, CuI films have exhibited a polycrystalline nature, having lattice parameters of a = b = c = 6.03 Å, with a prominent characteristic peak at 25.5° corresponding to the crystallite (111) plane. The FESEM and AFM results revealed that CuI films have granular surface morphology. The Hall effect measurement revealed the p-type nature of the grown CuI film, having a carrier concentration of ~ 10¹⁹ cm⁻³ for all four conditions of gas flow, and the highest mobility has been obtained to be 8.90 cm² V⁻¹ s⁻¹. The I–V measurements have shown the rectifying nature of the CuI/Si heterojunctions and good response toward UV light illuminations. The PL spectroscopy indicated the intense blue emission bands (413 nm), whereas the band broadening appeared for the red region (726 nm), and the right shifting occurred for a lower Ar flow rate. [ABSTRACT FROM AUTHOR]