Tailoring the Structural, Optical and Electrical Properties of Mn Doped ZnO Thin Films for Gas Sensing Response

Abstract

This manuscript presents a study on the photoinduced and gas sensing response of Mn-doped ZnO thin films (Zn1−xMnxO, x = 5, 10 mol %) synthesized using the spin coating method. The fabricated thin films were characterized to investigate their structural, bonding, optical, surface morphology, electrical, and gas sensing properties. SEM images displayed a homogeneous surface morphology across the fabricated films with typical grain size ranging from 25 to 30 nm. Optical absorption spectra demonstrated a variation in the optical band gap, ranging from 3.41 eV to 3.87 eV, indicating the tunability of the optical properties with the Mn doping concentration. Photoluminescence (PL) spectra exhibited Near Band Edge emission, as well as blue and green emission peaks, which can be attributed to the presence of defects and impurities in the Mn-doped ZnO thin films. The photoinduced effect was observed through the variation in I–V characteristics due to the excitation of electron-hole pairs, highlighting the influence of Mn doping on the charge transport properties of the thin films. Additionally, the gas sensing response of the Mn-doped ZnO thin films to hydrogen gas was investigated. The results indicated an improved gas sensing response with increasing Mn concentration in the doped ZnO thin films, suggesting the active role of Mn in enhancing the sensitivity of ZnO to hydrogen gas. Based on these findings, Mn-doped ZnO thin films show promise for application in gas sensors.