DUV and VUV light emitters have a variety of applications, such as in ozone cleaners, UV sterilization, etc. Rocksalt-Structured (RS) MgZnO alloys have attracted much attention as candidate materials for the solid-state DUV and VUV emitters. In this study, successful growths of atomically-flat single crystalline RS-MgZnO films on (001) MgO substrates by the mist chemical vapor deposition method and observation of DUV emission were demonstrated. Further improvements in its crystalline quality resulted in the predominate observation of cathodoluminescence (CL) peak at around 199-210 nm. The CL spectra showed relatively high equivalent internal quantum efficiencies of 2.5–11% for the DUV near-band-edge emission.
We proposed recently a new RF-MBE method called droplet elimination by radical-beam irradiation (DERI) for growing high-quality InN-based III-nitride films. DERI consists of two growth processes: a metal-rich growth process (MRGP) and a droplet elimination process (DEP). In InGaN growth, Ga was preferentially and selectively captured from the Ga/In wetting layer and droplets during MRGP. Then, excess In was swept out from the growing InGaN surface. The swept In was transformed to InN, epitaxially grown on top of InGaN during DEP using nitrogen radical beam irradiation. By repeating this process, an InN/InGaN MQW structure was successfully fabricated. Thick and uniform InGaN films were also successfully obtained by additionally irradiating the same Ga beam flux as that in MRGP even during DEP. When the irradiated Ga/N* beam flux ratio in DEP was changed from that in MRGP, an InxGa1-xN/InyGa1-yN MQW structure was successfully fabricated.