Browsing by Subject "Activation energy"

Now showing 1 - 6 of 6

Open Access
Experimental and theoretical investigation of phosphorus in-situ doping of germanium epitaxial layers
(Elsevier, 2013) Yu, H. -Y.; Battal, E.; Okyay, Ali Kemal; Shim, J.; Park J. -H.; Baek, J. W.; Saraswat, K. C.
We investigate phosphorus in-situ doping characteristics in germanium (Ge) during epitaxial growth by spreading resistance profiling analysis. In addition, we present an accurate model for the kinetics of the diffusion in the in-situ process, modeling combined growth and diffusion events. The activation energy and pre-exponential factor for phosphorus (P) diffusion are determined to be 1.91 eV and 3.75 × 10-5 cm2/s. These results show that P in-situ doping diffusivity is low enough to form shallow junctions for high performance Ge devices.
Open Access
Infrared photoluminescence from TlGaS2 layered single crystals
(Wiley - V C H Verlag GmbH & Co., 2004) Yuksek, N. S.; Gasanly, N. M.; Aydınlı, Atilla; Ozkan, H.; Acikgoz, M.
Photolimuniscence (PL) spectra of TlGaS2 layered crystals were studied in the wavelength region 500-1400 nm and in the temperature range 15-115 K. We observed three broad bands centered at 568 nm (A-band), 718 nm (B-band) and 1102 nm (C-band) in the PL spectrum. The observed bands have half-widths of 0.221, 0.258 and 0.067 eV for A-, B-, and C-bands, respectively. The increase of the emission band half-width, the blue shift of the emission band peak energy and the quenching of the PL with increasing temperature are explained using the configuration coordinate model. We have also studied the variations of emission band intensity versus excitation laser intensity in the range from 0.4 to 19.5 W cm-2. The proposed energy-level diagram allows us to interpret the recombination processes in TlGaS2 crystals.
Open Access
Low-frequency noise behavior at reverse bias region in InAs/GaSb superlattice photodiodes on mid-wave infrared
(SPIE, 2013) Tansel, T.; Kutluer, K.; Muti, Abdullah; Salihoğlu, Ömer; Aydınlı, Atilla; Turan, R.
We describe a relationship between the noise characterization and activation energy of InAs/GaSb superlattice Mid- Wavelength-Infrared photodiodes for different passivation materials applied to the device. The noise measurements exhibited a frequency dependent plateau (i.e. 1/f-noise characteristic) for unpassivated as well as Si3N4 passivated samples whereas 1/f-type low noise suppression (i.e. frequency independent plateau) with a noise current reduction of more than one order of magnitude was observed for SiO2 passivation. For reverse bias values below -0.15V, the classical Schottky-noise calculation alone did not appear to describe the noise mechanism in a SL noise behavior, which shows a divergence between theoretically and experimentally determined noise values. We identify that, the additional noise appears, with and without passivation, at the surface activation energy of < 60 meV and is inversely proportional to the reverse bias. This is believed to be caused by the surface dangling-bonds (as well as surface states) whose response is controlled by the applied reverse bias. The calculated noise characteristics showed a good agreement with the experimental data. © 2013 SPIE.
Open Access
Surface recombination noise in InAs / GaSb superlattice photodiodes
(IOP Institute of Physics Publishing, 2013) Tansel, T.; Kutluer, K.; Muti, A.; Salihoglu, Ö.; Aydınlı, Atilla; Turan, R.
The standard Schottky noise approach alone is not sufficient to describe the noise mechanism in an InAs/GaSb superlattice photodetector at reverse negative bias. The additional noise identified appears at surface activation energies below 60meV and is inversely proportional to the reverse bias. In order to satisfactorily explain the experimental data, we hereby propose the existence of a surface recombination noise that is a function of both the frequency and bias. The calculated noise characteristics indeed show good agreement with the experimental data.
Open Access
Thermally stimulated currents in layered Ga4SeS3 semiconductor
(2004) Aytekin, S.; Yuksek, N.S.; Goktepe, M.; Gasanly, N.M.; Aydınlı, Atilla
Thermally stimulated current (TSC) measurements are carried out on nominally undoped Ga4SeS3 layered semiconductor samples with the current flowing along the c-axis in the temperature range of 10 to 150 K. The results are analyzed according to various methods, such as curve fitting, initial rise and Chcn's methods, which seem to be in good agreement with each other. Experimental evidence is found for the presence of three trapping centers in Ga4SeS3 with activation energies of 70, 210 and 357 meV. The calculation yielded 7.9 × 10-21,7.0 × 10 -19 and 1.5 × 10-13 cm2 for the capture cross section, and 1.6 × 1010, 6.5 × 1010 and 1.2 × 1011 cm-3 for the concentration of the traps studied. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinlteim.
Open Access
XPS and water contact angle measurements on aged and corona-treated PP
(John Wiley & Sons, Inc., 1999) Süzer, S.; Argun, A.; Vatansever, O.; Aral, O.
Effects of corona treatment and aging on commercially produced corona discharged polypropylene (PP) films were followed via surface sensitive roughness analysis by atomic force microscopy (AFM), water contact angle (WCA), and X-ray photoelectron spectroscopic (XPS) measurements. Roughness analysis by AFM gave similar results for both untreated and corona-treated samples. The measured water contact angle decreased after corona treatment but increased with aging. XPS findings revealed that corona treatment caused an increase in the O-containing species on the surface of the films, but the measured O/C atomic ratio decreased with aging. The angle dependence of the observed XPS O/C atomic ratio further revealed that surface modifications by the corona treatment were buried into the polymer away from the surface as a function of aging. This is attributed to a surface rearrangement of the macromolecules in agreement with the findings of Garbassi et al. on oxygen-plasma-treated polypropylene.