Crystal defects observed by the etch-pit method and their effects on Schottky-barrier-diode characteristics on $(\bar{2}01)$ β-Ga₂O₃

Abstract

A pixel array of vertical Schottky-barrier diodes (SBDs) was fabricated and measured on the surface of a β-Ga2O3 single crystal. Subsequently, etch pits and patterns were observed on the same surface. Three types of etch pits were discovered: (1) a line-shaped etch pattern originating from a void and extending toward the [010] direction, (2) an arrow-shaped etch pit whose arrow’s head faces toward the [102] direction and, (3) a gourd-shaped etch pit whose point head faces toward the [102] direction. Their average densities were estimated to be 5 × 102, 7 × 104, and 9 × 104 cm−2, respectively. We confirmed no clear relationship between the leakage current in SBDs and these crystalline defects. Such results are obtained because threading dislocations run mainly in the [010] growth direction and do not go through the sample plate.

Vertical Geometry, 2-A Forward Current Ga2O3 Schottky Rectifiers on Bulk Ga2O3 Substrates

“…Oshima et al [37] found a spatial correlation between dicing-induced defects and large reverse leakage currents in diodes fabricated in those areas on (001) oriented substrates. Kasu et al [36] reported densities of etch pits above 10 4 cm −2 whose presence did not directly correlate with increased reverse leakage current in similar diodes on (001) oriented substrates. Dislocation defects along the [010] direction were found to act as paths for leakage current, while the Si doping did not affect this dislocationrelated leakage current.…”

Revelation of Dislocations in β‐Ga2O3 Substrates Grown by Edge‐Defined Film‐Fed Growth

“…This technique has been widely used to investigate dislocation densities and dislocation types for semiconductors such as 4H‐SiC and GaN . For β‐Ga 2 O 3 , several groups have reported that hot H 3 PO 4 solution can form etch pits on the surface outcrops of dislocations . In our previous studies, we have found that molten alkali solution could enhance defect‐selective chemical etching process for 4H‐SiC and GaN, in comparison with acid solution.…”

Wet etching in β-Ga2O3 bulk single crystals

“…They found three types of defects in EFG-grown crystals including edge dislocation arrays on (2̄01), plate-like nanopipes on (010) and twin lamellae (regular large twins) in crystal. Kasu et al fabricated a pixel array of vertical SBDs on the entire surface of (2̄01) 75 and (01̄0) 76 oriented β-Ga 2 O 3 wafers with H 3 PO 4 as an etchant at 140 °C. On the (2̄01) surface, they identified three types of etch pits and patterns, and measured an average density of 5 × 10 2 cm −2 .…”