Dielectric Reliability and Interface Trap Characterization in MOCVD grown In-situ Al$_2$O$_3$ on $\beta$-Ga$_2$O$_3$

TL;DR

This study demonstrates the in-situ MOCVD growth of high-quality Al$_2$O$_3$ on $eta$-Ga$_2$O$_3$, characterizing its dielectric reliability, interface traps, and long-term stability with a focus on high-temperature deposition processes.

Contribution

It introduces a novel high-temperature in-situ MOCVD process for Al$_2$O$_3$ on $eta$-Ga$_2$O$_3$ and evaluates its dielectric reliability and lifetime.

Findings

High breakdown field (~10 MV/cm) of the dielectric.

10-year lifetime under 3.5 MV/cm stress field.

Effective interface trap characterization methods.

Abstract

In this article, we investigate the in-situ growth of Al$_2$O$_3$ on $\beta$-Ga$_2$O$_3$ using metal-organic chemical vapor deposition (MOCVD) at a high temperature of 800{\deg}C. The Al$_2$O$_3$ is grown within the same reactor as the $\beta$-Ga$_2$O$_3$, employing trimethylaluminum (TMAl) and O$_2$ as precursors without breaking the vacuum. We characterize the shallow and deep-level traps through stressed capacitance-voltage (C-V) and photo-assisted C-V methods. The high-temperature deposited dielectric demonstrates an impressive breakdown field of approximately 10 MV/cm. Furthermore, we evaluate the reliability and lifetime of the dielectrics using time-dependent dielectric breakdown (TDDB) measurements. By modifying the dielectric deposition process to include a high-temperature (800{\deg}C) thin interfacial layer and a low-temperature (600{\deg}C) bulk layer, we report a 10-year lifetime under a stress field of 3.5 MV/cm along a breakdown field of 7.8 MV/cm.