Investigation of electrical transport mechanisms in an n-CdIn2Se4/Pt thin film Schottky diode fabricated by pulsed laser deposition

Abstract

This investigation focuses on the fabrication of an n-CdIn₂Se₄/Pt thin film Schottky diode using the pulsed laser deposition technique. The typical grazing incidence X-ray diffractogram displays a sharp and bright 〈1 1 1〉 characteristic reflection, confirming the formation of polycrystalline CdIn₂Se₄ thin films. Various microstructural parameters have been calculated for the CdIn₂Se₄ thin films using the most prominent 〈1 1 1〉 reflection. Hall measurement examination confirmed the n-type conductivity of the CdIn₂Se₄ thin films. Characterization of the voltage–current curve of the vacuum-fabricated n-CdIn₂Se₄/Pt thin film Schottky diode confirms the presence of a typical Schottky diode-type junction between CdIn₂Se₄ and platinum with a good rectification ratio. The principal conducting mechanism of the produced n-CdIn₂Se₄/Pt thin film Schottky diode is thermionic emission at lower applied biases (≤0.5 V), while the space charge limited conduction mechanism is dominant at higher biases (>0.5 V). The ideality factor values for the n-CdIn₂Se₄/Pt thin film Schottky diode are in the range of 1.4819 to 1.8102, depending on the temperature (300 K ≤ T ≤ 342 K). The zero-bias barrier height and effective Richardson's constant of the n-CdIn₂Se₄/Pt thin film Schottky diode are ≃0.8652 eV and ≃1.8771 × 10⁵ A m⁻² K², respectively. The effective density of permitted energy levels is ≃1.5491 × 10²⁴ m⁻³ in the conduction band of the n-CdIn₂Se₄ thin films. Additionally, characterization of the voltage–capacitance curve of the n-CdIn₂Se₄/Pt thin film Schottky diode revealed its zero bias built-in diffusion potential (≃0.8178 V), donor impurity concentration (≃5.9132 × 10²¹ m⁻³), and flat-band barrier height (≃0.9525 eV). Based on Anderson's model, several electrical transport parameters were applied to depict the theoretical energy band diagram of the n-CdIn₂Se₄/Pt thin film Schottky diode. The functional groups present in the CdIn₂Se₄ thin films deposited on a platinum thin film substrate were determined using Fourier transform infrared spectroscopy.