2D Small Hole Polarons in Ga2O3

It is well known that holes in oxides such as Ga2O3 localize and distort the lattice, forming small polarons. Here we explore the formation of polarons in (100) Ga2O3 nanolayers, which have been experimentally demonstrated. Using density functional theory at the hybrid functional level, we show that polarons can localize on oxygen atoms, with two of the symmetrically inequivalent (3-fold coordinated) O sites leading to stable polarons and the 4-fold coordinated position being metastable. This metastable polaron requires the breaking of a Ga-O bond and leads to a large displacement of a Ga atom. The combination of such a large displacement and a 2D layer should allow for experimental observation by using high-resolution transmission electron microscopy.