Search

Pt/(100) β-Ga2O3 Schottky barrier diodes were fabricated using a plate cleaved from the crystal grown by Czochralski method. Their electroconductive and photoelectric characteristics were studied. The following values were obtained: the Schottky barrier height (1.69/1.62/1.74 eV), ideality coefficient (1.09/1.14), saturation current density (9.91 × 10–15 A/cm2), diode series resistance (7.98 kΩ), and net donor concentration [(1.8–2.4) × 1018 cm–3]. The diodes demonstrate a high rectification ratio of 1010 at an applied voltage of ± 1 V and a relatively low experimental value of the leakage current density ∼10–11 A/cm2. These structures are solar-blind and also capable of operating in self-powered mode. The diodes are highly sensitive to short-wave ultraviolet radiation with a wavelength λ ≤ 265 nm. The maximum values of responsivity (20.4 A/W), external quantum efficiency (1.2 × 104%), and detectivity (9.6 × 1015 Hz0.5 × cm × W–1) of diodes were registered under exposure to irradiation at λ = 210 nm and at applied voltage of −1 V. The responsivity and external quantum efficiency values in the self-powered operation mode were 12.3 A/W and 7.2 × 103%, respectively. The diodes showed low rise and decay times in self-powered operation mode for photodiode based on Ga2O3: 14 and 30 ms, respectively. [ABSTRACT FROM AUTHOR]

The structural and gas-sensitive properties of n-N SnO2/κ(ε)-Ga2O3:Sn heterostructures were investigated in detail for the first time. The κ(ε)-Ga2O3:Sn and SnO2 films were grown by the halide vapor phase epitaxy and the high-frequency magnetron sputtering, respectively. The gas sensor response and speed of operation of the structures under H2 exposure exceeded the corresponding values of single κ(ε)-Ga2O3:Sn and SnO2 films within the temperature range of 25–175 °C. Meanwhile, the investigated heterostructures demonstrated a low response to CO, NH3, and CH4 gases and a high response to NO2, even at low concentrations of 100 ppm. The current responses of the SnO2/κ(ε)-Ga2O3:Sn structure to 104 ppm of H2 and 100 ppm of NO2 were 30–47 arb. un. and 3.7 arb. un., correspondingly, at a temperature of 125 °C. The increase in the sensitivity of heterostructures at low temperatures is explained by a rise of the electron concentration and a change of a microrelief of the SnO2 film surface when depositing on κ(ε)-Ga2O3:Sn. The SnO2/κ(ε)-Ga2O3:Sn heterostructures, having high gas sensitivity over a wide operating temperature range, can find application in various fields. [ABSTRACT FROM AUTHOR]

The electrical conductivity of pseudohexagonal ε(κ)‐Ga2O3 films under different ambient gases (H2, NO2, O2, and CO) is studied in a range of temperatures from 400 to 550 °C. The exposure of ε(κ)‐Ga2O3 to reducing gases such as H2 and CO results in a reversible increase in current and conductance. The exposure to the oxidizing gases such as NO2 and O2 has the opposite effect. The maximum response to reducing gases (H2 and CO) is observed at 500 °C and to oxidizing gases at 550 and 450 °C for NO2 and O2, respectively. The highest sensitivity to H2 is achieved at low applied voltages (≤7.9 V). In contrast, the highest sensitivity to NO2 is observed at high applied voltages. The response and recovery times and temporal drift of ε(κ)‐Ga2O3 characteristics under different ambient are estimated. Polycrystalline ε(κ)‐Ga2O3 exhibits the semiconducting mechanism of electron transport at high temperatures. A qualitative model of the gas‐sensing effect based on the modulation of electron concentration near the surface region of ε(κ)‐Ga2O3 due to the chemisorption of gas molecules is described. Tin doping of ε(κ)‐Ga2O3 increases the response to H2 at the temperature range from 25 to 550 °C. [ABSTRACT FROM AUTHOR]