“…Electrical performance, such as μ fe , on-current ( I on ), subthreshold slope ( SS ), and on/off current ratio ( I on/off ) tends to decrease steadily as O p increases. This is because when O p increases during the deposition, the oxygen vacancy ( V o ) inside the thin film is suppressed 23 . Therefore, carrier concentration decreases with the suppression of V o , and electrical properties degrade.…”
Section: Resultsmentioning
confidence: 99%
“…As described above, the XPS O1s peak, electrical characteristics, and DOSs result from decreasing V o as O p increases. This implies that the energy bandgap can be adjusted indirectly according to O p and, thus, the carrier concentration or the Fermi level can be controlled 23 . Therefore, to derive the energy bandgap directly, each energy level has been measured using ultra-violet photoelectron spectroscopy (UPS), Kelvin probe force microscopy (KPFM), and high-resolution electron energy loss spectroscopy (HR-EELS).Figure 4Calculated density of states (DOSs) versus activation energy ( E a ) for a-SZTO TFTs as function of O p .…”
The variation in energy bandgaps of amorphous oxide semiconducting SiZnSnO (a-SZTO) has been investigated by controlling the oxygen partial pressure (Op). The systematic change in Op during deposition has been used to control the electrical characteristics and energy bandgap of a-SZTO. As Op increased, the electrical properties degraded, while the energy bandgap increased systematically. This is mainly due to the change in the oxygen vacancy inside the a-SZTO thin film by controlling Op. Changes in oxygen vacancies have been observed by using X-ray photoelectron spectroscopy (XPS) and investigated by analyzing the variation in density of states (DOS) inside the energy bandgaps. In addition, energy bandgap parameters, such as valence band level, Fermi level, and energy bandgap, were extracted by using ultraviolet photoelectron spectroscopy, Kelvin probe force microscopy, and high-resolution electron energy loss spectroscopy. As a result, it was confirmed that the difference between the conduction band minimum and the Fermi level in the energy bandgap increased systematically as Op increases. This shows good agreement with the measured results of XPS and DOS analyses.
“…Electrical performance, such as μ fe , on-current ( I on ), subthreshold slope ( SS ), and on/off current ratio ( I on/off ) tends to decrease steadily as O p increases. This is because when O p increases during the deposition, the oxygen vacancy ( V o ) inside the thin film is suppressed 23 . Therefore, carrier concentration decreases with the suppression of V o , and electrical properties degrade.…”
Section: Resultsmentioning
confidence: 99%
“…As described above, the XPS O1s peak, electrical characteristics, and DOSs result from decreasing V o as O p increases. This implies that the energy bandgap can be adjusted indirectly according to O p and, thus, the carrier concentration or the Fermi level can be controlled 23 . Therefore, to derive the energy bandgap directly, each energy level has been measured using ultra-violet photoelectron spectroscopy (UPS), Kelvin probe force microscopy (KPFM), and high-resolution electron energy loss spectroscopy (HR-EELS).Figure 4Calculated density of states (DOSs) versus activation energy ( E a ) for a-SZTO TFTs as function of O p .…”
The variation in energy bandgaps of amorphous oxide semiconducting SiZnSnO (a-SZTO) has been investigated by controlling the oxygen partial pressure (Op). The systematic change in Op during deposition has been used to control the electrical characteristics and energy bandgap of a-SZTO. As Op increased, the electrical properties degraded, while the energy bandgap increased systematically. This is mainly due to the change in the oxygen vacancy inside the a-SZTO thin film by controlling Op. Changes in oxygen vacancies have been observed by using X-ray photoelectron spectroscopy (XPS) and investigated by analyzing the variation in density of states (DOS) inside the energy bandgaps. In addition, energy bandgap parameters, such as valence band level, Fermi level, and energy bandgap, were extracted by using ultraviolet photoelectron spectroscopy, Kelvin probe force microscopy, and high-resolution electron energy loss spectroscopy. As a result, it was confirmed that the difference between the conduction band minimum and the Fermi level in the energy bandgap increased systematically as Op increases. This shows good agreement with the measured results of XPS and DOS analyses.
“…Based on the reference for materials having indirect band gaps [19,23], the optical band gaps of HfTiO and IGZO are determined by applying the Tauc model, and the Davis and Mott model in the high absorbance region:…”
Section: Resultsmentioning
confidence: 99%
“…The IGZO was also deposited by sputtering on both Si and glass substrates by using a single target of InGaZnO 4 with diameter of 60 mm. The RF power was 40 W, while the working pressure was kept constant at 0.5 Pa. All the detailed experimental procedure can be found in our previous publications [18,19]. All as-deposited films were amorphous as determined by X-ray diffraction (XRD) and showed optical transmittance of $80% in the visible region, as shown in Fig.…”
“…The latest rapid growth of microwave communications necessitate dielectric materials, which have a high dielectric constant, low dielectric loss and better thermal stability in microwave frequencies [2,3]. Titanium dioxide is believed to be one of the most inspiring materials for the application potential in solar energy conservation and energy storage devices since it has high refractive index leading to a high hiding power, whiteness, resistance to photo corrosion, high dielectric constant, useful photo catalytic properties, chemical stability, low cost and non-toxicity [4][5][6][7][8][9].…”
In this study, we investigated temperature and voltage dependence of dielectric properties and ac electrical conductivity (σ ac ) of (AuZn)/TiO 2 /p-GaAs(110) metal-insulator-semiconductor structures in the temperature range of 80-290 K using the capacitance-voltage C À V ð Þ and conductance-voltage ð G x À V Þ measurements at 1 MHz. The intersection/crossing behaviour of C-V plots at sufficiently high forward biases and the increase in σ ac with increasing temperature was attributed to the lack of sufficient number of enough free charge carriers at low temperatures. The values of the dielectric constant (ε′), dielectric loss (ε″), loss tangent tan d ð Þ, ac electrical conductivity (σ ac ), the real and imaginary parts of electric modulus (M 0 ; M 00 ) were found to be strong functions of temperature and applied bias voltage. The Cole-Cole plots between M 0 vs: M 00 have shown only one semicircle for each temperature. This indicates one of the relaxation processes was suppressed and this can be attributed to the surface polarization effect. On the other hand, M 00 vs. V plot has a peak for each temperature. The Ln r ac ð Þ vs. q kT plots revealed two linear regions with different slopes for sufficiently high forward biases (0.0, 0.5, and 1.0 V) which correspond to low (80-200 K) and moderate/intermediate (230-290 K) temperatures. Thus, the values of activation energy (E a ) were obtained from the slope of these Arrhenius plots for two linear regions as 87.3 and 3.4 meV, respectively, at 1.0 V. On the other hand, Mott plots have only one linear region except for 260 and 290 K and Mott parameters were determined from these plots at 0.0, 0.5 and 1.0 V.
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