Computational and experimental approach for investigating the microstructural parameters of a cadmium indium selenide (α-CdIn2Se4) ternary semiconducting compound

Abstract

Several properties are carefully considered before choosing a semiconducting material for the fabrication of a thin-film electronic device. Cadmium indium selenide (CdIn₂Se₄) is a ternary semiconducting compound belonging to the II–III₂–VI₄ family, where II = zinc (Zn), cadmium (Cd), or mercury (Hg); III = aluminium (Al), gallium (Ga), or indium (In); and VI = sulphur (S), selenium (Se), or tellurium (Te). The Cambridge serial total energy package (CASTEP) module, within the framework of density functional theory (DFT) using the PBE-GGA (Perdew–Burke–Ernzerhof generalized gradient approximation), was used to compute the elastic constants for the CdIn₂Se₄ ternary semiconducting compound. Stoichiometric amounts of 5 N-pure (99.999%) Cd, In, and Se elements were used to synthesize the CdIn₂Se₄ compound using a microcontroller-based programmable high-temperature rotary furnace. X-ray diffraction (XRD) was used to examine the crystal structure and phase purity of the synthesized CdIn₂Se₄ ternary semiconducting compound. The synthesized CdIn₂Se₄ ternary semiconducting compound exhibited a high level of crystallinity, as evinced by its strong XRD peak intensity and narrow full width at half maximum (FWHM, β) of the diffraction peaks. Identification, indexing, and accurate mapping of the X-ray diffractogram peaks of CdIn₂Se₄ were successfully performed using ICDD card No. 01-089-2388. The synthesized CdIn₂Se₄ ternary semiconducting compound possessed a single-phase pseudo-cubic α-phase tetragonal structure (c ≃ a) with the P2m(111) crystallographic space group (SG). For the most prominent XRD peak (111), the stacking fault (SF) value of the ternary semiconducting compound CdIn₂Se₄ was determined to be 1.0267 × 10⁻³. For the preferred orientations of the crystallites along a crystal plane (hkl), the texture coefficient (C_i) of each XRD peak of the ternary semiconducting compound CdIn₂Se₄ was measured, yielding values close to unity (≃1). The degree of preferred orientation (Δ) for the ternary semiconducting compound CdIn₂Se₄ was found to be 9.6751 × 10⁻⁴. To gain insight into the growth behavior of the synthesized CdIn₂Se₄ ternary semiconducting compound, the Bravais theory was applied to compute the d-interplanar spacings (d_hkl), enabling inference on the significance of the (111) plane in the crystal structure of CdIn₂Se₄. The lattice constant (a) for the CdIn₂Se₄ ternary semiconducting compound was 0.5818 nm, corresponding to a cell volume of 0.1969 nm³, calculated using the Miller indices for the prominent (111) plane. Rietveld refinement (RR) of the XRD data for the ternary semiconducting compound CdIn₂Se₄ was performed using the FullProf Suite software. Several microstructural parameters of the CdIn₂Se₄ compound, including lattice parameter (a), crystallite size (D), lattice strain (ε), root mean square strain (ε_rms), dislocation density (δ), lattice stress (σ), and energy density (u), were determined. Additionally, bulk modulus (B_H), shear modulus (G_H), Young's modulus (y), Poisson's ratio (ν), elastic anisotropy, melting temperature (T_m), transverse sound velocity (v_t), longitudinal sound velocity (v_l), average wave velocity (v_m), and Debye temperature (θ_D) were derived for the CdIn₂Se₄ compound. Energy dispersive X-ray analysis (EDAX) with elemental mapping and a densitometer (pycnometer) confirmed the stoichiometry (with elemental distribution) and density (ρ) of the synthesized CdIn₂Se₄ compound, respectively. Room temperature (RT) (≃300 K) Fourier transform infrared (FTIR) spectroscopy in the wavenumber () range of 4000–400 cm⁻¹ confirmed the purity of the synthesized CdIn₂Se₄ ternary semiconducting compound by detecting the presence of functional group/s, if any, in the FTIR spectra. The findings obtained from the detailed investigation of the CdIn₂Se₄ compound may serve as a valuable reference for future researchers focused on device development. Accordingly, the authors have made a concerted effort to examine various properties of the CdIn₂Se₄ ternary semiconducting compound through both theoretical and experimental approaches. It is anticipated that researchers worldwide may utilize these results in the development of a wide range of electronic devices. The implications of the study are discussed.