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Conference Object Citation - WoS: 2Citation - Scopus: 2Temperature-Dependent Capacitance-Voltage Biasing of the Highly Tunable Tlgate2 Crystals(Elsevier Science Bv, 2012) Qasrawi, A. F.; Gasanly, N. M.The temperature effects on the capacitance-voltage characteristics as well as the room temperature capacitance-frequency characteristics of TlGaTe2 crystals are investigated. A very wide range of linearly varying tunable capacitance from 6.0 mu F to 60 pF was recorded. The capacitance-voltage characteristics, being recorded in the temperature range of 290-380 K, revealed a linear increase in the build in voltage associated with exponential decrease in the density of non-compensated ionized carriers with increasing temperature. The high temperature (up to 380 K) biasing ability, the linear tunability and the high dielectric constant values ( similar to 10(3)) make the TlGaTe2 crystals applicable in microelectronic components. (C) 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 9Investigation of the Electrical Parameters of Ag/P-tlgases Schottky Contacts(Elsevier, 2012) Qasrawi, A. F.; Gasanly, N. M.p-type TlGaSeS single crystal was used to fabricate a Schottky device. Silver and carbon metals were used as the Ohmic and Schottky contacts, respectively. The device which displayed wide RF band at 13.200 and narrow band at 62.517 kHz with Q value of 1.4 and of 6.3 x 10(4), respectively, is characterized by means of current (I)-voltage (V), capacitance (C)-voltage characteristics as well as capacitance-frequency (f) characteristics. The device series resistance, ideality factor and barrier height are determined from the I-Vcurve as 35.8 M Omega, 1.2 and 0.74 eV, respectively. The apparent acceptor density and the build in voltage of the device increased with increasing ac signal frequency. The high Q value, observed at 62.517 kHz. indicated a much lower rate of energy loss relative to the stored energy of the device. The energy loss (Q(-1)) is much less than 0.001% of the stored value. The device was tested and found to remain at the same mode of resonance for several hours. It never switched or ceased unless it was tuned off. (c) 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 12Citation - Scopus: 12Design and Characterization of Tlinse2 Varactor Devices(Elsevier, 2011) Qasrawi, A. F.; Aljammal, Faten G.; Taleb, Nisreen M.; Gasanly, N. M.TlInSe2 single crystal has been successfully prepared by the Bridgman crystal growth technique. The crystal, which exhibits compositional atomic percentages of 25.4%, 25.2% and 49.4% for TI, In and Se, respectively, is found to be of tetragonal structure with lattice parameters of a=0.8035 and c=0.6883 nm. The crystals were used to design radio frequency sensitive varactor device. The temperature dependence of the current-voltage characteristics of the device allowed the calculation of the room temperature barrier height and ideality factor as 0.87 eV and as 3.2, respectively. Rising the device temperature increased the barrier height and decreased the ideality factor. This behavior was attributed to the current transport across the metal-semiconductor interface. The capacitance of the device is observed to increase with increasing voltage and increasing temperature as well. The temperature activation of the capacitance starts above 82 degrees C with a temperature coefficient of capacitance being 1.08 x 10 (3) K (1). Furthermore, the capacitance of the device was observed to increase with increasing frequency up to a maximum critical frequency of 4.0 kHz, after which the capacitance decreased with increasing frequency. The behavior reflected the ability of maximum amount of charge holding being at a 4.0 kHz. The analysis of the capacitance-voltage characteristics at fixed frequencies reflected a frequency dependent barrier height and acceptors density. The decrease in the barrier height and acceptors density with increasing frequency is mainly due to the inability of the free charge to follow the ac signal. (C) 2011 Elsevier B.V. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 9Effect of Ytterbium, Gold and Aluminum Transparent Metallic Substrates on the Performance of the Ga2s3< Thin Film Devices(Elsevier Science Bv, 2017) Alharbi, S. R.; Qasrawi, A. F.In the current work, the structural, optical, dielectric and electrical properties of the Ga2S3 thin films which are deposited onto transparent thin Al, Yb and Au metal substrates are characterized by means of transmittance electron microscopy, X-ray diffraction, ultraviolet visible light spectroscopy and impedance spectroscopy techniques. The effects of the metallic substrates on the crystalline nature, energy band gap and dielectric spectra are also investigated. The modeling of the dielectric spectra allowed determining the effect of the Al, Yb and Au thin layers on the electron scattering time, the plasmon frequency, free electron density and drift mobility. In addition, a Yb/Ga2S3/Au Schottky barrier and All Ga2S3/Au back to back Schottky barrier devices (metal-semiconductor-metal (MSM) device) are fabricated and characterized by means of capacitance-voltage characteristics and capacitance and conductance spectra in the frequency range of 10-1800 MHz. While the Schottky barrier device displayed three distinct positions of resonance-antiresonance phenomena, the MSM device displayed one peak with narrow bandwidth of 10 MHz. The MSM devices exhibited an inversion, depletion and accumulation modes within a voltage range of 0.25 V width at 250 MHz. The study indicates the applicability of these device as smart capacitive switches, as Plasmon devices and as wavetraps. (C) 2017 Elsevier B.V. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5Dielectric and photo-dielectric properties of TlGaSeS crystals(indian Acad Sciences, 2014) Qasrawi, A. F.; Abu-Zaid, Samah F.; Ghanameh, Salam A.; Gasanly, N. M.The room temperature, dark and photo-dielectric properties of the novel crystals TlGaSeS are investigated in the frequency, intensity and biasing voltage having ranges of similar to 1-120 MHz, 14-40 klux and 0-1 V, respectively. The crystals are observed to exhibit a dark high frequency effective dielectric constant value of similar to 10.65 x 10(3) with a quality factor of similar to 8.84 x 10(4) at similar to 120 MHz. The dielectric spectra showed sharp resonance-antiresonance peaks in the frequency range of similar to 25-250 kHz. When photoexcited, pronounced increase in the dielectric constant and in the quality factor values with increasing illumination intensity are observed. Signal amplification up to similar to 33% with improved signal quality up to similar to 29% is attainable via photoexcitation. On the other hand, the illuminated capacitance voltage characteristics of the crystals reflected a downward shift in the voltage biasing and in the built-in voltage of the device that is associated with increase in the uncompensated carrier density. The increase in the dielectric constant with increasing illumination intensity is ascribed to the decrease in the crystal's resistance as a result of increased free carrier density. The light sensitivity of the crystals, the improved dielectric properties and the lower biasing voltage obtained via photoexcitation and the well-enhanced signal quality factor of the crystals make them promising candidates for optical communication systems.
