Structural characterization of threading dislocation in α-Ga2O3 thin films on c- and m-plane sapphire substrates

We discuss the structure of threading dislocations in α-Ga2O3 thin films grown on c- and m-plane sapphire substrates. The thickness-dependent threading dislocation density in both films directly affects the electrical properties of the films including carrier concentration and mobility. Two distinct types of threading dislocations are identified for each of the c- and m-plane α-Ga2O3 thin films. The c-plane α-Ga2O3 thin film shows Burgers vectors of 1 / 3 [ 1 1 ¯ 01 ] and 1 / 3 [ 11 2 ¯ 0 ], while the m-plane α-Ga2O3 thin film displays Burgers vectors of 1 / 3 [ 2 1 ¯ 1 ¯ 0 ] and 1 / 3 [ 1 1 ¯ 01 ]. This paper presents a detailed structure of the threading dislocations in α-Ga2O3, which has been little disclosed thus far mainly due to the difficulty in synthesizing the metastable α-Ga2O3.