Investigating the Electrical, Power Factor, and Figure of Merit Characteristics of Cadmium Oxide Nanostructures Fabricated via Thermal Evaporation in Vacuum

Abstract

A cadmium dioxide nanostructure was fabricated on silicon and quartz substrates through oblique angle deposition (OAD). The synthesis involved the initial thermal evaporation of high-purity cadmium metal films at varying deposition angles on the substrates, followed by a 1.5-hour oxidation process at 773 K in a conventional furnace to produce cadmium oxide nanostructures. X-ray diffraction (XRD) analysis revealed the development of crystalline structures within the cadmium oxide (CdO) films. The deposition angle exhibited a significant impact, influencing the preferred orientation along the (111) planes more substantially than the normal incident angle. I-V measurements and assessments of electrical conductivity were conducted under both light and dark conditions for the CdO films. The photocurrent generated in an oblique (Al/CdO/p-Si/Al) heterojunction exceeded that of a standard detector under illumination. The investigation explored the thermoelectric properties of CdO nanomaterials, including the figure of merit (M), power factor (P.F.), and Seebeck coefficient (S), for both normally deposited and obliquely deposited films. The results demonstrated an enhancement in the figure of merit with oblique deposition, potentially attributed to increased roughness, resulting in reduced thermal conductivity and an elevated figure of merit. All findings indicated superior performance for deposition angles (θº = 50º & 70º) in comparison to normal deposition (θº = 0º).