[19a-Z33-1~12] 21.1 Joint Session K "Wide bandgap oxide semiconductor materials and devices"

▼ [19a-Z33-7] Polycrystalline Defects Origin of Reverse Leakage Current in HVPE (001) β-Ga₂O₃ SBDs Identified by High Sensitive Emission Microscope

〇(D)Sayleap Sdoeung¹, Kohei Sasaki², Katsumi Kawasaki³, Jun Hirabayashi³, Akito Kuramata², Makoto Kasu¹ (1.Saga Univ., 2.Novel Crystal Technology, 3.TDK)

Keywords:beta-gallium oxide, crystal defects, Schottky barrier diode

β-Ga₂O₃ has a bandgap of 4.43–4.8 eV, which is wider than that of SiC and GaN; hence, it can be used to develop high-efficient high-power electronic devices. Recently, Sasaki et al. developed 20 A class SBDs with a low on-resistance of 6 mΩ cm². However, it has been observed that in the SBDs fabricated on a single 2’’ wafer, some show a higher reverse current and a lower breakdown voltage than their neighbors. Therefore, in this study we investigate the killer defects that are responsible for the reverse leakage current in HVPE (001) β-Ga₂O₃ SBDs via high-sensitive emission microscopy. An n-type β-Ga₂O₃ epitaxial layer grown by HVPE on a 2” EFG-grown (001) single-crystal wafer substrate. The net donor doping density, N_D-N_A, is 1.4 10¹⁶cm⁻³. The epitaxial thickness is ca. 10 μm. For the ohmic contact, Ti/Au was evaporated on the entire back face, whereas for the Schottky barrier (SB) contacts, Ni/Au was evaporated on the surface. Emission microscope image of the SBD #B1205 with a 500 μm diameter with a high reverse leakage current (density) of 38 μA ( 19.3 mA cm^-2) at 30 V shows two emission patterns, #1 and #2. AFM images shows that emission pattern #1 is polycrystalline defect which contains numerous domains. In cross-sectional SEM image shows a porous particle containing highly dense voids observed below the defect. In synchrotron X-ray topography the polycrystalline defect was seen as a butterfly contrast. The polycrystalline defect is found to be one of the main reverse leakage current paths of HVPE (001) β-Ga₂O₃ SBDs.