Elemental steps in the growth of thin β-Ga2O3 films on CoGa(1 0 0)

The oxidation of CoGa(1 0 0) at 700 K was studied by means of high resolution electron energy loss spectroscopy (EELS), scanning tunneling microscopy, low energy electron diffraction and Auger electron spectroscopy (AES). At 700 K, thin well-ordered β-Ga2O3 films grow on CoGa(1 0 0). The EEL spectrum of the Ga-oxide films exhibit Fuchs–Kliewer phonons at 305, 455, 645, and 785 cm−1. For low oxygen exposure (<0.2 L), the growth of oxide-islands starts at step edges and on defects. The oxide films have the shape of long, rectangular islands and are oriented in the [1 0 0] and [0 1 0] directions of the substrate. For higher oxygen exposure, islands of β-Ga2O3 are found also on the terraces. After an exposure of 200 L O2 at 700 K, the CoGa(1 0 0) surface is homogeneously covered with a thin film of β-Ga2O3.