【Device Papers】Sensing Performance Analysis of Passivated β-(AlₓGa₁₋ₓ)₂O₃ / Ga₂O₃ Schottky Diode Gas Sensor with Catalytic Metals at High Temperature

      Researchers from the Asansol Engineering College have published a dissertation titled "Sensing Performance Analysis of Passivated β-(Al_xGa_1-x)₂O₃/Ga₂O₃ Schottky Diode Gas Sensor with Catalytic Metals at High Temperature" in Journal of The Institution of Engineers (India): Series B.

Abstract

      Gallium oxide (Ga₂O₃) has garnered significant attention and emerged as a promising material for various applications, including gas sensors. Ga₂O₃’s wide bandgap, high electron mobility, thermal stability, and chemical resistance make it well-suited for detecting various gases with high sensitivity and selectivity. Its emergence in this field reflects its potential to address key challenges and meet the growing demand for efficient and reliable gas sensing technologies. Among various Ga₂O₃-based gas sensors, Schottky diodes have demonstrated superior sensing performance for a wide range of gases, including hydrogen, oxygen, nitrogen oxides, and volatile organic compounds. The effectiveness of highly significant technological functionality in enhancement-mode high voltage rectifiers and other technologically significant effects of the Metal-Oxide Field Compared to SiC or GaN, β-Ga₂O₃ has a higher critical electric field, which is advantageous for transistors. Out of the five polymorphs of Ga₂O₃, the β-polymorph is the one that has been studied and utilized the most, and in most cases, it is the stable form. The Schottky diode’s structure and interfacial properties provide spontaneous and piezoelectric polarisation effects. Consequently, a highly dense 2-DEG is produced that is extremely responsive to variations in surface states. Regarding Schottky sensors with different Pt thicknesses, active regions, and operating temperatures, it may be investigated how adding noble metals such as Pt, Pd, etc. affects their capacity to detect gases. The semiconductor’s reaction with the metal is one of the most crucial factors in determining Schottky barriers. Therefore, by selecting the appropriate electrode metal based on its reactivity with the semiconductor, sensor performance and the reliability and longevity of the devices can be optimized. The surface passivation with scandium oxide (Sc₂O₃) offers significant benefits for Ga₂O₃-based devices, including the enhancement of 2DEG density and improvement of device performance and reliability. Here, a physics-based analytical modelling technique has been proposed to inspect the (Al_xGa_1-x)₂O₃/Ga₂O₃ Schottky hetero-structure diode for applications that require extremely linear and sensitive gas sensing. Designing a sensor that has great linearity, a high level of sensitivity, and excellent detectivity at low gas concentration levels and lower temperatures is the main goal of the effort. The surface characteristics and hetero-interface are taken into account here. The primary method for modelling the device is to use the dependence of the two-dimensional electron gas (2-DEG) on surface charges influenced by the passivation layer of Sc₂O₃. The gas sensor electrode helps to determine the sensors’ sensitivity and other significant properties. On Ga₂O₃-based sensors, the proposed Schottky contact with catalytic electrodes like Pd, Pt, as well as other metals has been investigated. We simulated the sensor model based on Schottky diodes using Silvaco TCAD and were able to get V-I curves for various gas concentrations. In this case, Acetone vapor has been considered for this study. The response obtained from the V-I curves demonstrates a reaction of more than 85% under the influence of gas concentration (500 ppm) at a 0.97 V bias voltage. Additionally, we observed that temperature affected the sensor’s response for various Schottky contacts at different gas concentrations.

DOI：

https://doi.org/10.1007/s40031-024-01182-0