Characterization of band offset in α-(AlxGa1-x)2O3/ α-Ga2O3 heterostructures
Gallium Oxide is a promising material for power device applications. We focused on corundum structured gallium oxide (α-Ga<sub>2</sub>O<sub>3</sub>) and α-(Al<sub>x</sub>Ga<sub>1-x</sub>)<sub>2</sub>O<sub>3</sub>/ α-Ga<sub>2</sub>O<sub>3</sub> heterostructure devices. We prepared α-(Al<sub>x</sub>Ga<sub>1-x</sub>)<sub>2</sub>O<sub>3</sub> alloy and these laminate structures on c-plane sapphire substrates. The band offset of the α-Ga<sub>2</sub>O<sub>3</sub>/α-(Al<sub>x</sub>Ga<sub>1-x</sub>)<sub>2</sub>O<sub>3</sub> heterostructure was measured by X-ray photoelectron spectroscopy (XPS). The band alignment was estimated to be type I with very narrow valence-band offset energy.
Band gap and function engineering for novel functional alloy semiconductors: Bloomed as magnetic properties at room temperature with α-(GaFe)2O3
Highly crystalline corundum structured α-(Ga0.42Fe0.58)2O3 alloy thin film showed magnetic properties at room temperature. Microstructure analysis of cross-sectional transmission electron microscope (TEM) observation and TEM energy dispersive X-ray spectroscopy measurement indicated that different crystal phase could not be detected as well as there is no remarkable phase separating area, that is, Fe and Ga ions are distributed uniformly in the film. Magnetic measurements were performed on α-(Ga1−xFex)2O3 (x = 0.24, 0.44, 0.58, 1.00) alloy thin films at 110 K. The induced magnetic moment per a Fe ion of α-(Ga0.42Fe0.58)2O3 at 5000 Oe is about 6 times larger than α-Fe2O3 thin film. Compared to the α-Fe2O3 thin films, the value of coercivity is also about 6 times in α-(Ga0.42Fe0.58)2O3, in contrast, there is no significant difference in value of coercivity of α-(Ga1−xFex)2O3 (x = 0.24, 0.44, 1.00) thin films. These means that the origin of magnetism is not the separation region of α-Fe2O3 in α-(Ga0.42Fe0.58...
Monte carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions
The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte Carlo simulations for the unpolarized and single-polarized Drell-Yan pp{sup ({up_arrow}}{sup )}{yields}{mu}{sup +}{mu}{sup -}X at different center-of-mass energies in both configurations where the antiproton beam hits a fixed proton target or it collides on another proton beam. The goal is to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the high energy storage ring (HESR) at GSI. It is important to study the feasibility of such experiments at HESR in order to demonstrate that interesting spin physics can be explored already using unpolarized antiprotons.