Effect of Al_0.1Ga_0.9As thickness on the structural, optical, thermal, and electrical properties of (Al_0.1 Ga _0.9As)/GaAs heterojunctions

Al_0.1Ga_0.9As nano-films of various thicknesses were deposited on GaAs substrate and examined using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), UV–Visible spectrophotometry, Photoluminescence (PL), Electrochemical Impedance Spectroscopy (EIS), and Photothermal Deflection (PTD). The PTD technique is used to analyze the effect of Al_0.1Ga_0.9As thickness on thermal properties and showed its sensitivity to weak structural changes. By increasing the Al_0.1Ga_0.9As thickness, the crystallinity was degraded, an infrared emission centered at 997.4 nm whose intensity is the highest for 50 nm was observed. A pn junction was formed for thicknesses higher than 400 nm, the band gap was increased from 1.59 to 1.68 eV. The thermal conductivity increased from 35.3 to 37.3 W m^{− 1} K⁻¹ and the thermal diffusivity increased from 0.195 to 0.22 cm² s⁻¹. As a result of this investigation, the Al_0.1Ga_0.9As/GaAs can be considered for potential applications in photoelectric and thermoelectric devices.