Growth Study of New Complex Oxide PbOxSe1-x Thin Films by Oxygen Plasma-Assisted Molecular Beam Epitaxy

In this work, we introduce the growth of a new complex oxide lead oxy-chalcogenide (PbOxSe1-x) thin film using an oxygen plasma-assisted molecular beam epitaxy method. Freshly cleaved BaF2(111) wafers were used as the substrates for this growth study. Systematic characterization of X-ray diffraction peaks, Raman shifts, absorption spectra, scanning electron microscopic imaging, and Hall measurements were conducted to elucidate the structural, optical, and electric properties of the as-grown PbOxSe1-x thin films. Specifically, X-ray diffraction measurements revealed that PbOxSe1-x films maintained the same rock-salt crystal structure as the PbSe semiconductor, but a slight shift in the lattice parameter was observed. A blue shift in the optical absorption edge also suggests that the inclusion of oxygen atoms led to the formation of a ternary compound crystal structure. Furthermore, all PbOxSe1-x thin films were observed to be polycrystalline in nature and displayed preferred [100] orientated grains. Slight variations in LO and TO phonon peak positions were also observed under Raman spectroscopy, signifying the presence of lead-oxygen bonding. This new type of complex oxide thin film has never been reported and could potentially be used to develop advanced optoelectronic devices, including mid-infrared photodetectors and light-emitting devices.