In this work, a self-powered, solar-blind photodetector, based on InZnSnO (IZTO) as a Schottky co... more In this work, a self-powered, solar-blind photodetector, based on InZnSnO (IZTO) as a Schottky contact, was deposited on the top of Si-doped β-Ga2O3 by the sputtering of two-faced targets with InSnO (ITO) as an ohmic contact. A detailed numerical simulation was performed by using the measured J–V characteristics of IZTO/β-Ga2O3 Schottky barrier diodes (SBDs) in the dark. Good agreement between the simulation and the measurement was achieved by studying the effect of the IZTO workfunction, β-Ga2O3 interfacial layer (IL) electron affinity, and the concentrations of interfacial traps. The IZTO/β-Ga2O3 (SBDs) was tested at a wavelength of 255 nm with the photo power density of 1 mW/cm2. A high photo-to-dark current ratio of 3.70×105 and a photoresponsivity of 0.64 mA/W were obtained at 0 V as self-powered operation. Finally, with increasing power density the photocurrent increased, and a 17.80 mA/W responsivity under 10 mW/cm2 was obtained.
Transactions on Electrical and Electronic Materials, 2022
Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating tech... more Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating technique. Zinc acetate dihydrate and 2-methoxyethanol were used as precursor with different molar concentrations, 0.2 M, 0.3 M and 0.6 M. The effect of precursor concentration on the structural and optical properties, transmission (T), reflection (R), optical bandgap (Eg), Urbach energy (EU), refractive index (n), extinction coefficient (k), single-oscillator energy (E0), dispersion energy (Ed), moments M−1 and M−3, dielectric constant (ε) and optical conductivity (σ), of the ZnO thin films was studied and investigated. Although, the transmittance, slightly, decreased and the reflectance increased, as the molar concentration increased, the measurements showed that all samples have high transparency and low reflectivity in the visible range which make them suitable for solar cells applications. It is also found that, as the molarity increased, the ZnO thin films exhibited lower Eg and EU and higher Ed, M−1 and M−3.
In this work, the temperature-dependent parameters of Ni/β-Ga2O3 Schottky barrier diode (SBD) wer... more In this work, the temperature-dependent parameters of Ni/β-Ga2O3 Schottky barrier diode (SBD) were analyzed and modeled. The simulation is to elucidate the physical phenomenon behind this temperature dependence. At room temperature, the deviation of SBD parameters from the ideal case is due to the Schottky barrier height ( ϕ B ) inhomogeneity. A model is developed for this inhomogeneity in which an interfacial defected layer (IDL) is formed. Defects (extrinsic states) are related to plasma and Ar atom bombardment used in the confined magnetic field-based sputtering to realize the Ni Schottky contact diffusion in β-Ga2O3. Ni diffuses, upon annealing, to compensate defects in this IDL. It was found that the Schottky barrier height ( ϕ B ) and threshold voltage V Th decrease with increasing temperature. This decrease is related to intrinsic and extrinsic states (plasma and Ar bombardment). However, the ideality factor (η) increases which is related to the series resistance (R S) increa...
In this work, a detailed numerical simulation is carried out to model the current–voltage charact... more In this work, a detailed numerical simulation is carried out to model the current–voltage characteristics of a nickel/β-Ga2O3 Schottky barrier diode at different temperatures. These SBDs are produced using confined magnetic-field-based sputtering to deposit the nickel (Ni) Schottky contact of the diode. This method reduces the thickness of the defect area created by plasma and argon bombardment, and consequently, the electrical characteristics are less affected by temperature changes or annealing (i.e. the device is more stable). During annealing, Ni diffuses into β-Ga2O3. A model for this diffusion is proposed in this work, in which Ni diffusion reduces the defects produced by plasma and argon bombardment by filling the Ga vacancy. Furthermore, Ni diffusion produces a new interfacial compound, namely (N i x G a 1 − x ) 2 O 3 at the interface between the Ni and the β-Ga2O3. This new compound layer has different properties than those of β-Ga2O3, in particular, those of the bandgap an...
ECS Journal of Solid State Science and Technology, 2020
The reverse leakage current under high reverse voltage of a Ni/β-Ga 2 O 3 Schottky barrier diode ... more The reverse leakage current under high reverse voltage of a Ni/β-Ga 2 O 3 Schottky barrier diode (SBD) is numerically modelled and compared to measurements. universal Schottky tunnelling, thermionic emission and image-force lowering were taken into account. Furthermore, when type conversion under high reverse voltage has occurred at the top interface between Ni and β-Ga 2 O 3 and the SBD behaved as P–i–N diode, band to band tunnelling is proposed in association with the usually used Selberherr’s Impact ionization to model avalanche breakdown. The obtained breakdown voltage and specific on-resistance value are 434 V and 2.13 mΩ·cm2, respectively, fairly close to measurement values of 440 V and 2.79 mΩ·cm2. Optimization is performed based on the insertion of an intrinsic layer between Ni and the β-Ga 2 O 3 drift layer. It was found that 0.4 μm gave better Baliga’s figure of merit of 9.48107 W·cm−2 with breakdown voltage and specific on-resistance of 465 V and 2.28 mΩ·cm2, respectively...
Amorphous indium gallium zinc oxide (a-IGZO) are promising for developing thin film transistors (... more Amorphous indium gallium zinc oxide (a-IGZO) are promising for developing thin film transistors (TFTs) because of their large electron mobility, small threshold voltage (Vth), and low temperature fabrication process. In this study, we have investigated the effect of near valance band defects on the output parameters of a-IGZO TFTs by using two-dimensional TCAD numerical simulation. It was found that donor defects near the valance band have no effect. The degradation of the mobility also causes degradation in the TFT performance. Acceptor defects states near valance band is the reason of positive Vth shift. It is therefore concluded that near valance band defects are not donor defects but acceptor defects with a Gaussian distribution which can also degrade the mobility.
Amorphous In–Ga–Zn–O (a-IGZO) thin films with (1:1:2) molar fraction were grown using spin coatin... more Amorphous In–Ga–Zn–O (a-IGZO) thin films with (1:1:2) molar fraction were grown using spin coating deposition at room temperature on glass substrates. The effect of three rotation speeds (3000, 4000, 5000 rpm) of the spin coating machine on the films structure and transparency is studied by X-ray diffraction and UV–visible transmission. It was found that the film obtained at 3000 rpm has the best transmission which is over 80 % in the visible wavelength range. The absorbance at ultra violet wavelengths is used to calculate the band gap of the 3000 rpm sample and the obtained value is about 3.6 eV. The reflectance at visible and infrared wavelengths is used to calculate the refractive index. An average value of 2.45 was found. The calculated optical parameters were used as optical input parameters for modeling an a-IGZO(n)/µ-Si(p) heterojunction solar cell using a commercial software. The cell exposed to AM1.5 spectrum presents promising optimal outputs parameters: a short-circuit current density Jsc of 32.41 mA cm−2, an open-circuit voltage Voc of 0.47 V, a fill factor FF of 38 % and a conversion efficiency η of 5.79 %.
In this work, a self-powered, solar-blind photodetector, based on InZnSnO (IZTO) as a Schottky co... more In this work, a self-powered, solar-blind photodetector, based on InZnSnO (IZTO) as a Schottky contact, was deposited on the top of Si-doped β-Ga2O3 by the sputtering of two-faced targets with InSnO (ITO) as an ohmic contact. A detailed numerical simulation was performed by using the measured J–V characteristics of IZTO/β-Ga2O3 Schottky barrier diodes (SBDs) in the dark. Good agreement between the simulation and the measurement was achieved by studying the effect of the IZTO workfunction, β-Ga2O3 interfacial layer (IL) electron affinity, and the concentrations of interfacial traps. The IZTO/β-Ga2O3 (SBDs) was tested at a wavelength of 255 nm with the photo power density of 1 mW/cm2. A high photo-to-dark current ratio of 3.70×105 and a photoresponsivity of 0.64 mA/W were obtained at 0 V as self-powered operation. Finally, with increasing power density the photocurrent increased, and a 17.80 mA/W responsivity under 10 mW/cm2 was obtained.
Transactions on Electrical and Electronic Materials, 2022
Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating tech... more Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating technique. Zinc acetate dihydrate and 2-methoxyethanol were used as precursor with different molar concentrations, 0.2 M, 0.3 M and 0.6 M. The effect of precursor concentration on the structural and optical properties, transmission (T), reflection (R), optical bandgap (Eg), Urbach energy (EU), refractive index (n), extinction coefficient (k), single-oscillator energy (E0), dispersion energy (Ed), moments M−1 and M−3, dielectric constant (ε) and optical conductivity (σ), of the ZnO thin films was studied and investigated. Although, the transmittance, slightly, decreased and the reflectance increased, as the molar concentration increased, the measurements showed that all samples have high transparency and low reflectivity in the visible range which make them suitable for solar cells applications. It is also found that, as the molarity increased, the ZnO thin films exhibited lower Eg and EU and higher Ed, M−1 and M−3.
In this work, the temperature-dependent parameters of Ni/β-Ga2O3 Schottky barrier diode (SBD) wer... more In this work, the temperature-dependent parameters of Ni/β-Ga2O3 Schottky barrier diode (SBD) were analyzed and modeled. The simulation is to elucidate the physical phenomenon behind this temperature dependence. At room temperature, the deviation of SBD parameters from the ideal case is due to the Schottky barrier height ( ϕ B ) inhomogeneity. A model is developed for this inhomogeneity in which an interfacial defected layer (IDL) is formed. Defects (extrinsic states) are related to plasma and Ar atom bombardment used in the confined magnetic field-based sputtering to realize the Ni Schottky contact diffusion in β-Ga2O3. Ni diffuses, upon annealing, to compensate defects in this IDL. It was found that the Schottky barrier height ( ϕ B ) and threshold voltage V Th decrease with increasing temperature. This decrease is related to intrinsic and extrinsic states (plasma and Ar bombardment). However, the ideality factor (η) increases which is related to the series resistance (R S) increa...
In this work, a detailed numerical simulation is carried out to model the current–voltage charact... more In this work, a detailed numerical simulation is carried out to model the current–voltage characteristics of a nickel/β-Ga2O3 Schottky barrier diode at different temperatures. These SBDs are produced using confined magnetic-field-based sputtering to deposit the nickel (Ni) Schottky contact of the diode. This method reduces the thickness of the defect area created by plasma and argon bombardment, and consequently, the electrical characteristics are less affected by temperature changes or annealing (i.e. the device is more stable). During annealing, Ni diffuses into β-Ga2O3. A model for this diffusion is proposed in this work, in which Ni diffusion reduces the defects produced by plasma and argon bombardment by filling the Ga vacancy. Furthermore, Ni diffusion produces a new interfacial compound, namely (N i x G a 1 − x ) 2 O 3 at the interface between the Ni and the β-Ga2O3. This new compound layer has different properties than those of β-Ga2O3, in particular, those of the bandgap an...
ECS Journal of Solid State Science and Technology, 2020
The reverse leakage current under high reverse voltage of a Ni/β-Ga 2 O 3 Schottky barrier diode ... more The reverse leakage current under high reverse voltage of a Ni/β-Ga 2 O 3 Schottky barrier diode (SBD) is numerically modelled and compared to measurements. universal Schottky tunnelling, thermionic emission and image-force lowering were taken into account. Furthermore, when type conversion under high reverse voltage has occurred at the top interface between Ni and β-Ga 2 O 3 and the SBD behaved as P–i–N diode, band to band tunnelling is proposed in association with the usually used Selberherr’s Impact ionization to model avalanche breakdown. The obtained breakdown voltage and specific on-resistance value are 434 V and 2.13 mΩ·cm2, respectively, fairly close to measurement values of 440 V and 2.79 mΩ·cm2. Optimization is performed based on the insertion of an intrinsic layer between Ni and the β-Ga 2 O 3 drift layer. It was found that 0.4 μm gave better Baliga’s figure of merit of 9.48107 W·cm−2 with breakdown voltage and specific on-resistance of 465 V and 2.28 mΩ·cm2, respectively...
Amorphous indium gallium zinc oxide (a-IGZO) are promising for developing thin film transistors (... more Amorphous indium gallium zinc oxide (a-IGZO) are promising for developing thin film transistors (TFTs) because of their large electron mobility, small threshold voltage (Vth), and low temperature fabrication process. In this study, we have investigated the effect of near valance band defects on the output parameters of a-IGZO TFTs by using two-dimensional TCAD numerical simulation. It was found that donor defects near the valance band have no effect. The degradation of the mobility also causes degradation in the TFT performance. Acceptor defects states near valance band is the reason of positive Vth shift. It is therefore concluded that near valance band defects are not donor defects but acceptor defects with a Gaussian distribution which can also degrade the mobility.
Amorphous In–Ga–Zn–O (a-IGZO) thin films with (1:1:2) molar fraction were grown using spin coatin... more Amorphous In–Ga–Zn–O (a-IGZO) thin films with (1:1:2) molar fraction were grown using spin coating deposition at room temperature on glass substrates. The effect of three rotation speeds (3000, 4000, 5000 rpm) of the spin coating machine on the films structure and transparency is studied by X-ray diffraction and UV–visible transmission. It was found that the film obtained at 3000 rpm has the best transmission which is over 80 % in the visible wavelength range. The absorbance at ultra violet wavelengths is used to calculate the band gap of the 3000 rpm sample and the obtained value is about 3.6 eV. The reflectance at visible and infrared wavelengths is used to calculate the refractive index. An average value of 2.45 was found. The calculated optical parameters were used as optical input parameters for modeling an a-IGZO(n)/µ-Si(p) heterojunction solar cell using a commercial software. The cell exposed to AM1.5 spectrum presents promising optimal outputs parameters: a short-circuit current density Jsc of 32.41 mA cm−2, an open-circuit voltage Voc of 0.47 V, a fill factor FF of 38 % and a conversion efficiency η of 5.79 %.
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