【Epitaxy Papers】Orientation-dependent β-Ga₂O₃ heterojunction diode with atomic layer deposition (ALD) NiO

      Researchers from the University of California Santa Barbara have published a dissertation titled "Orientation-dependent β-Ga₂O₃ heterojunction diode with atomic layer deposition (ALD) NiO" in Applied Physics Letters.

Abstract

      This work reports the demonstration of ALD-deposited NiO/β-Ga₂O₃ heterojunction diodes (HJDs) on low doped (N_D-N_A ≤ 1 × 10¹⁶ cm⁻³) drift layers and highly doped (001) & (100) n⁺ substrates (N_D-N_A > 1 × 10¹⁸ cm⁻³) with experimental observation of a parallel-plane junction electric field as high as 7.5 MV/cm, revealing a crystal orientation dependence in β-Ga₂O₃. We use a metalorganic precursor, bis(1,4-di-tert-butyl-1,3-diazadienyl) (nickel Ni(^tBu2DAD)₂), with ozone (O₃) to deposit NiO. The NiO/β-Ga₂O₃ HJD on the 7.7 μm-thick HVPE-grown drift region exhibited an on-state current density of ∼20 A/cm² at 5 V, ∼10⁻⁸ A/cm² reverse leakage at low reverse bias (−5 V), and a rectifying ratio (J_on/J_off) of ∼10⁹. The HJD broke down at ∼2.2 kV reverse bias, corresponding to a ∼3.4 MV/cm parallel-plane junction electric field, with a noise-floor reverse leakage (10⁻⁸–10⁻⁶ A/cm², nA) at 80% of the device's catastrophic breakdown voltage. The NiO/β-Ga₂O₃ HJDs on n⁺ (001) & (100) highly doped substrates exhibited breakdown voltages at 12.5–16.0 and 28.5–70.5 V, respectively, with extracted critical electric fields (E_C) at 2.30–2.76 and 4.33–7.50 MV/cm, revealing a substrate crystal orientation dependence on breakdown electric field for β-Ga₂O₃. The 7.5 MV/cm E_C reported here is one of the highest parallel-plane junction electric fields reported in literature.

DOI：

https://doi.org/10.1063/5.0285622