Etch pit formation on β-Ga2O3 by molten KOH+NaOH and hot H3PO4 and their correlation with dislocations

Abstract

The chemical etch pitting method is a powerful technique to reveal dislocations in semiconductor materials; however, a reliable etchant has not been established for β-Ga2O3. In this work, we performed a comparative study of two etchants, molten KOH+NaOH and hot H3PO4, to reveal dislocations from the (−201) surface. Using transmission electron microscopy, it was determined that KOH+NaOH could reveal all grown-in dislocations. The dislocation outcrops were located at the pit cores. The pit shape, specifically, its symmetry in the [010] direction, had a close correlation with the line direction of the dislocations but there was no simple correlation with the Burgers vector. On comparing H3PO4 with KOH+NaOH on the same sample, the results indicated that both etchants could reveal dislocations with a large angle to the (−201) surface but H3PO4 could not reveal dislocations nearly parallel to this surface. Surface damage induced by polishing produced etch pits in both etchants with smaller dimensions than those of the grown-in dislocations.