Codeposition of deuterium ions with beryllium oxide at elevated temperatures

Deuterium-loaded BeO films were produced by sputtering the beryllium target with 10 keV Ne ions in D2 gas at a pressure of approximately 1 Pa. The sputtered beryllium reacts – on the substrate surface – with the residual oxygen, thus forming a beryllium oxide layer. Biasing the substrate negatively with respect to the target provides the simultaneous bombardment of the growing film surface with D ions formed by Ne–D2 collisions. Substrate potential governs the maximum energy of ions striking the growing film surface while its size governs the flux density. According to X-ray photoelectron spectroscopy (XPS), electron probe microanalysis (EPMA) and reflection high energy electron diffraction (RHEED) data, the beryllium is deposited in the form of polycrystalline hcp-BeO layers with negligible (about 1 at.%) carbon and neon retention. Thermal desorption spectroscopy (TDS) data shows a strong deuterium bonding, with a desorption peak at 950 K, in the films deposited at −50 and −400 V substrate potentials. In addition, a relatively high ratio D/BeO≈0.2 has been found in the BeO films even at a substrate temperature of 800 K. Microstructural features of mixed Be–C–O films are presented as well.