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

Chemical etching and synchrotron X-ray topography (XRT) are used to reveal dislocations in commercial edge-defined film-fed growth (EFG) β-Ga₂O₃ substrates with the (010)-oriented or the (−201)-oriented surface. Different etchants and etching temperatures are compared, and the optimal condition is found to be etching in a eutectic KOH + NaOH solution at 200 °C for 2 min. By counting the surface features formed by etching, dislocation density is estimated to be in the range of 6 × 10⁴–1 × 10⁶ cm⁻², viewed from the (010) surface, and 8 × 10⁴cm⁻², viewed from the (−201) surface. A comparison of dislocation contrast observed by XRT and etch pits has confirmed that the above chemical etching is capable of revealing dislocations accurately.