Study of temperature-dependent copper iodide thin film by thermal evaporation system

Abstract The development of heterostructure devices has gained significant attention towards scientific communities in the present time. This article reports on the effective use of the horizontal thermal evaporation (TE) method to successfully fabricate copper iodide (CuI) films on silicon (Si) substrates. By using the TE technique, CuI-based heterojunctions have been fabricated in this research . CuI exhibits semiconductor qualities of the p-type, making it a promising option for optoelectronic devices in the future. The temperature was varied from room temperature (RT) to 230 °C to synthesise the CuI/Si heterojunction. The structural, morphological, optical, and electrical analyses have been carried out with various substrate temperatures. The x-ray diffraction (XRD) data shows that the CuI films have demonstrated a polycrystalline character and have lattice parameters of 6.03 Å. The Raman spectroscopy study shows the microstructural analysis of CuI films. The field emission scanning electron microscopy (FESEM) study reveals the variation of grain size and shape with synthesis temperature. The atomic force microscope (AFM) was used to estimate the surface roughness. The CuI films were found to be p-type by the Hall effect measurement. The sample synthesised at 130 °C shows the highest mobility of 83.12 cm 2 V −1 s −1 with a carrier concentration of 10 19 cm −3 . The UV-visible (UV–vis) spectroscopy measurements show good absorption of UV light by the CuI thin films. The CuI/Si heterojunctions are rectifying, as demonstrated by the I-V measurements, and those respond well to UV light irradiation.