Investigation of Schottky barrier height using area as parameter: Effect of hydrogen peroxide treatment on electrical optical properties of Schottky diode

Abstract RF sputtered 25 nm ZnO thin film surface treated with H2O2 has produced the Schottky diodes of improved electrical and optical properties. The enhancement is associated with adsorbed and introduced oxygen at the film's surface and in bulk while H2O2 treatment as revealed by the XPS analysis. Further, H2O2 treatment also has improved the ZnO thin film's surface morphology, crystal structure, and optical properties studied by XRD, SEM, and PL measurement. The experimentally measured energy band gap is compared with density functional theory computation-based result to find the possible cause behind the change in edge excitation energy band after treatment. Besides, an alternative method by considering the Schottky diode area as a parameter is introduced to calculate barrier height. The five diodes average barrier height, calculated by the conventional Schottky model, was lower than the barrier height obtained by this proposed method. This result is obtained for the diodes fabricated on the nontreated and treated sample. The conventional and proposed methods showed Schottky diodes potential barrier lowering under UV illumination, and it was associated with the change in carrier density and desorption of adsorbed oxygen on the ZnO surface. The treated surface's low conductivity and high oxygen concentration governed the superior UV detection capability of Schottky diodes fabricated on it. The literature demonstrates many similar studies for large thicknesses of ZnO 150–1000 nm but not on ultra-thin (25 nm) ZnO film, even though the UV light can penetrate ZnO approximately to this depth.