【International Papers】Dielectric reliability and interface trap characterization in MOCVD grown in situ Al₂O₃ on β-Ga₂O₃

      Researchers from the University of California Santa Barbara have published a dissertation titled "Dielectric reliability and interface trap characterization in MOCVD grown in situ Al₂O₃ on β-Ga₂O₃" in Applied Physics Letters.

Corresponding Author Introduction

      Ph.D. in Electrical Engineering, The Ohio State University

      M.Sc. (Hons) in Physics, Birla Institute of Technology & Science (BITS)-Pilani

      B.E. (Hons.) in Electrical and Electronics Engineering, Birla Institute of Technology & Science (BITS)- Pilani.

      Prof. Krishnamoorthy's group works at the intersection of materials, electrical engineering and physics to study and engineer next-generation (ultra)wide band gap semiconductors such as Gallium Oxide. We are interested in epitaxial growth, electronic transport, design/modeling, micro/nano fabrication, and characterization of electronic/optoelectronic devices for a wide range of applications such as power electronics, high frequency electronics and ultra-violet optoelectronics.

Abstract

      In this article, we investigate the in situ growth of Al₂O₃ on β-Ga₂O₃ using metal-organic chemical vapor deposition at a high temperature of 800 °C. The Al₂O₃ is grown within the same reactor as the β-Ga₂O₃, employing trimethylaluminum and O₂ 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 catastrophic breakdown field of approximately 10 MV/cm. Furthermore, we evaluate the reliability and lifetime of the dielectrics using time-dependent dielectric breakdown measurements. By modifying the dielectric deposition process to include a high-temperature (800 °C) thin interfacial layer and a low-temperature (600 °C) bulk layer, we report a 10-year lifetime under a stress field of 3.5 MV/cm along a catastrophic breakdown field of 7.8 MV/cm.

Summary

      In summary, we present in situ Al₂O₃ growth via MOCVD at higher temperatures as a superior alternative to conventional deposition methods. We also introduce a hybrid dielectric method, combining an 800°C interfacial layer with a 600°C bulk dielectric. Capacitance–voltage measurements were used to assess interface quality, revealing that the 800°C dielectric outperforms others in near interface trap states and catastrophic breakdown field strength. However, the hybrid dielectric (sample B) shows better uniformity than 800°C dielectric and better interface quality than the 600°C dielectric, making it a more balanced option. This in situ dielectric deposition on β-Ga₂O₃ promises enhanced performance for future high-performance MOSFETs.