High breakdown electric field in $\text{Ba}_{\mathrm{x}}\text{Sr}_{1-\mathrm{x}}\text{TiO}_{3}/\text{SiO}_{2}$ dielectric stack formed on (010) $\beta$-Ga2O3 substrates

Development of high permittivity dielectrics is critical for the electrical field management in devices made with ultra-wide bandgap (UWBG) semiconductors such as
$\beta$
-Ga
2
O
3
. High permittivity dielectrics are typically deposited at high temperatures and their integration with low temperature atomic-layer deposition (ALD) processed dielectrics offers a significant challenge. In this article, we studied the quality of high permittivity dielectric
$\text{Ba}_{\mathrm{x}}\text{Sr}_{1-\mathrm{x}}\text{TiO}_{3}$
deposited using pulsed laser deposition (PLD) on ALD-grown SiO
2
and investigated the electronic properties of this dielectric stack formed on (010)
$\beta$
-Ga
2
O
3
Sn-doped substrates. We varied the PLD deposition parameters (such as temperature and target composition) and identified conditions that can withstand an effective breakdown electric field (
$E_{eff, BD}$
; calculated in reference to SiO
2
) of > 30 MV/cm within the dielectric stack while maintaining low leakage ≤ 10
⁻⁸
A/cm
²
at
$E_{eff} < 5.8-7.6\ \text{MV}/\text{cm}$
. Interface defect characterization in the devices exhibited a high defect density at the SiO
2
/
$\beta$
-Ga
2
O
3
interface.