Effect of isothermal annealing and visible-light illumination on the AC-impedance behavior of undoped selenium thin films

Determination of Optical Properties of Undoped Amorphous Selenium (a-Se) Films by Dielectric Modeling of Their Normal-Incidence Transmittance Spectra

“…The as-deposited Se films were all pinhole-free and had smooth surfaces without traces of cracks. The structure and surface morphology of as-deposited Se-films were studied at room temperature by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, the results of which revealed their amorphous structure, in good agreement with XRD diffractograms and SEM micrographs of Se-films prepared in our laboratory under same conditions (Abdul-Gader et al, 1998;Abdul-Gader & Nigmatullin, 2001;Al-Hamarneh et al, 2009). We designate the www.ccsenet.org/apr Applied Physics Research Vol.…”

“…Extrinsic doping increases glass transformation and crystallization temperatures of a-Se films, often referred to as stabilized a-Se when slightly doped with arsenic (As), to limit deterioration of their performance with temperature and time when are incorporated in solid-state devices (Tan, 2006;Tan et al, 2007;Tan et al, 2006;Vautier et al, 1988;Bettstelleret al, 1993;Mulama et al, 2014;Benkhedir, 2006;Solieman et al, 2014). Reduction of time-ageing and glass transformation of undoped a-Se films, and hence virtuous performance in devices integrating them, can also be realized by growing and/or annealing them at temperatures around 70 , but their electrical resistivity is significantly reduced (Abdul-Gader et al, 1998;Abdul-Gader & Nigmatullin, 2001;Al-Hamarneh et al, 2009). To fabricate undoped a-Se films, care should be taken not to grow them at temperatures higher than 45 , not to expose it to intense nuclear radiations or illumination with photon energies close to its band-gap energy (El-Zawawi & Abd-Alla, 1999;Ishida & Tanaka, 1997;Poborchii et al, 1998;, and to store them under vacuum and dark conditions to impede deterioration and drastic change of their properties.…”