Backside Illumination of an Electronic Photo Ionization Detector Realized by UV Transparent Thin Films

Abstract

LaB6/ITO films were prepared by magnetron sputtering technique on borosilicate glass substrates. The transmittance of ITO and LaB6/ITO films was analyzed by using UV/VIS spectrophotometer, whereby the sheet resistance of the ITO films was measured by four point probes. The effect of temperature and post-annealing processes on ITO film properties optimizing UV transparency and sheet resistance were investigated in detail. ITO films with an optimized thickness of 31 nm exhibited a low sheet resistance of 64 Ω/sq and a high ultraviolet transmittance of 81% at a wavelength of 365 nm. The additional LaB6 layer controls the UV transmittance behavior of the bilayer structure of LaB6/ITO by improving the photon absorption with thicker LaB6 films. The work function of LaB6 (32 nm)/ITO films with a value of 4.98 eV was measured by ultraviolet photoelectron spectroscopy (UPS).