Effect of localized states on the photocurrent in amorphous silicon alloys

Bebek, Mehmet Bahadır
Amorphous Silicon alloy thin films were deposited by plasma enhanced chemical vapor deposition technique. In order to make optoelectronic measurements, diode structures were fabricated by depositing transparent metal electrodes. Theoretical background of localized density of states in the mobility gap and photocurrent mechanisms has been revisited. In light of this, time of flight technique, using transient photocurrent, was utilized to determine mobility in extended states and characteristic energy of tail states in the film. The actual density of states (DOS) in the mobility gap of the deposited films was determined by using absorption coefficients obtained via constant photocurrent measurements. Finally, adverse effects of small Oxygen incorporation on mobility and DOS were observed.


Optical properties of silicon based amorphous thin films
Akaoğlu, Barış; Katırcıoğlu, Bayram; Department of Physics (2004)
Silicon based hydrogenated amorphous semiconducting (intrinsic and n/p doped a-Si:H and a-Si1-xCx:H) thin films have been deposited by plasma enhanced chemical vapor deposition (PECVD) system. In order to analyze the optical response of these amorphous films, intrinsic optical absorption mechanisms have resumed and spectral variations of absorption coefficient ?(E) are derived. The exponential variation of absorption coefficient for energies below the band edge is discussed in the frame of randomly distribu...
Effects of gold-induced crystallization process on the structural and electrical properties of germanium thin films
Kabacelik, Ismail; Kulakci, Mustafa; Turan, Raşit; ÜNAL, NURİ (Wiley, 2018-07-01)
Gold-induced (Au-) crystallization of amorphous germanium (-Ge) thin films was investigated by depositing Ge on aluminum-doped zinc oxide and glass substrates through electron beam evaporation at room temperature. The influence of the postannealing temperatures on the structural properties of the Ge thin films was investigated by employing Raman spectra, X-ray diffraction, and scanning electron microscopy. The Raman and X-ray diffraction results indicated that the Au-induced crystallization of the Ge films ...
Effects of tail states on the conduction mechanisms in silicon carbide thin films with high carbon content
SEL, KIVANÇ; AKAOĞLU, BARIŞ; Atilgan, Ismail; Katircioglu, Bayram (Elsevier BV, 2011-03-01)
Hydrogenated amorphous silicon carbide (a-SiCx:H) films of different carbon content (x) were deposited by radio frequency plasma enhanced chemical vapor deposition (PECVD) system. Apart from the X-ray photoelectron spectroscopy (XPS) and UV-Visible transmission analyses, the resistivity measurements between 293 K and 450 K were emphasized to assess the eventual transport mechanisms. The film resistivities are unexpectedly found relatively low, especially for high carbon content. In the frame of exclusive ba...
OZKAN, H; ALBISS, BA; HAMDAN, N; MENARD, A (Springer Science and Business Media LLC, 1994-12-01)
The effect of gamma-irradiation and silver doping on the properties of YBCO superconductors has been studied by electrical resistance measurements and x-ray diffraction techniques. The zero-resistance superconducting transition temperature of (YBCO)(1-x)Ag-x systematically increase by about 2 K with an increase of Ag content up to x = 0.04. Further increase in Ag content decreases the transition temperature. The normal-state resistance decreases up to a factor of 3.4 with an increase of Ag content. No signi...
Effect of heat treatment on the stress and structure evolution of plasma deposited boron nitride thin films
Anutgan, T. Aliyeva; Anutgan, M.; Wdemir, O.; Atilgan, I.; Katircioglu, B. (Elsevier BV, 2008-03-25)
Boron nitride (BN) thin films are deposited at 573 K by plasma enhanced chemical vapor deposition (PECVD) with ammonia (NH3) and hydrogen diluted diborane (15% B2H6 in H-2) source gases. UV-visible and Fourier transform infrared (FTIR) spectroscopies together with surface profilometry are used for the film characterization. These films are hydrogenated (BN:H) whose hydrogen content is pursued following the 1.5 h annealing process at 748 K, 923 K and 1073 K under nitrogen atmosphere. Hydrogen escape with the...
Citation Formats
M. B. Bebek, “Effect of localized states on the photocurrent in amorphous silicon alloys,” M.S. - Master of Science, Middle East Technical University, 2009.