Low Interface Trapped Charge Density for AlO/β-GaO (001) Metal-Insulator-Semiconductor Capacitor

In this letter, high-performance Al2O3/
$\beta$
-Ga2O3 (001) metal-insulator-semiconductor (MIS) capacitor has been demonstrated. The capacitance-voltage (C–V) curves of the Al2O3/
$\beta$
-Ga2O3 (001) MIS capacitor remain stable under different measurement frequencies. The leakage current density is lower than
$2.0 \times 10^{-8}$
A/cm2 when the gate voltage is in the range of −5~13 V. The fixed charge and trapped charge densities in Al2O3 film are
$4.4 \times 10^{12}$
and
$6.0 \times 10^{11}$
cm−2, respectively. Average and minimum interface trapped charge density (
${\mathrm {D}}_{it}$
) for Al2O3/
$\beta$
-Ga2O3 (001) interface has been extracted to be as low as
$3.3 \times 10^{11}$
and
$2.3 \times 10^{11}$
cm−2 eV−1 via the Terman method, respectively. The low
${\mathrm {D}}_{it}$
is probably attributed to the modification of vacancy defects and the introduction of hydroxyl groups at the Al2O3/
$\beta$
-Ga2O3 (001) interface after piranha solution pretreatment for
$\beta$
-Ga2O3.