High-Performance ZrO₂/β-Ga₂O₃ (001) Metal–Insulator–Semiconductor Capacitors

In this study, we have fabricated high-performance metalinsulatorsemiconductor (MIS) capacitor using atomic layer-deposited ZrO2/beta-gallium oxide ( $\beta $ -Ga2O3) (001) heterojunction. The energy band alignment for the ZrO2/ $\beta $ -Ga2O3 heterojunction and electrical properties for the ZrO2/ $\beta $ -Ga2O3 MIS capacitor are investigated. Valence band offset ( $\Delta {E}_{V}$ ) and conduction band offset ( $\Delta {E}_{C}$ ) for the ZrO2/ $\beta $ -Ga2O3 heterojunction, determined by X-ray photoelectron spectroscopy (XPS) technique, are −0.42 and 1.42 eV, respectively. Its band alignment configuration exhibits a type II (staggered gap) structure. Gate leakage current and frequency-dependent capacitancevoltage (C–V) characteristics for the ZrO2/ $\beta $ -Ga2O3 MIS capacitor are investigated. The ZrO2/ $\beta $ -Ga2O3 MIS capacitor demonstrates a low gate leakage current. The PooleFrenkel (PF) conduction model is employed to elucidate the gate leakage current mechanism. No significant frequency dispersion is observed based on the frequency-dependent C–V characteristics. The fixed charge and trapped charge densities in the ZrO2 film are calculated to be $7.9\times 10^{{12}}$ and $1.27\times 10^{{12}}$ cm $^{-{2}}$ , respectively. The minimum interface trapped charged density is extracted to be $4.1\times 10^{{10}}$ cm $^{-{2}}\cdot \text { eV}^{-{1}}$ at an energy of 0.6 eV below the conduction band of $\beta $ -Ga2O3, representing the lowest reported value for the dielectric/ $\beta $ -Ga2O3 (001) interface. These results indicate the formation of high-quality ZrO2 film on the $\beta $ -Ga2O3, making it a potential candidate as gate dielectrics in $\beta $ -Ga2O3 power devices.