Cathodoluminescence real-color imaging and spectroscopy were employed to study the properties of Ga(2)O(3) nanowires grown with different Sn/Ga ratios. The structures grown under Sn-rich conditions show large spectral emission variation, ranging from blue to red, with a green transition zone. Spectral emission changes correlate with changes in the chemical composition and structure found by energy dispersive spectroscopy and electron diffraction. A sharp transition from green to red emission correlates with a phase transition of beta-Ga(2)O(3) to polycrystalline SnO(2). The origin of the green emission band is discussed based on ab initio calculation results.

Autonomous systems are increasingly used to provide situational awareness and long-term environment monitoring. Photovoltaics (PV) are favored as a long-endurance power source for many of these applications. To date, the use of PV is limited to space and terrestrial (dry-land) installations. The need for a persistent power source also exists for underwater (UW) systems, which currently rely on surface PV arrays or batteries. In this paper, we demonstrate that high-bandgap-InGaP solar cells can provide useful power UW.

In-grown stacking faults in n-type 4H-SiC epitaxial layers have been investigated by real-color cathodoluminescence imaging and spectroscopy carried out at room and liquid helium temperatures. Stacking faults with 8H stacking order were observed, as well as double layer and multilayer 3C-SiC structures and a defect with an excitonic band gap at 2.635 eV. It was found that 8H stacking faults and triangular surface defects can be generated from similar nucleation sources. Time-resolved measurements reveal that compared to defect-free regions, the carrier lifetimes are severely reduced by the presence of stacking faults corresponding to triangular surface defects and three-dimensional 3C-SiC inclusions.

Although β-Ga 2 O 3 thin films and nanowires (NWs) show promise as very stable and reliable active components for high temperature gas sensors, their use at room temperatures is limited due to poor electrical conductivity. To address this problem, we grew Sn-doped β-Ga 2 O 3 nanowires by the vapor-liquid-solid (VLS) approach. Sn-doped β-Ga 2 O 3 NWs with diameters of 100-250 nm retained the monoclinic β-Ga 2 O 3 structure, though photoluminescence (PL) emission was red-shifted by up to 50 nm relative to the deep defect band typically observed for pure β-Ga 2 O 3 NWs. When higher amounts of Sn were introduced, individual Ga 2 O 3 -SnO 2 heterostructures (HS) self-assembled, to form three distinctive parts: monocrystalline Sn-doped β-Ga 2 O 3 , poorly crystalline Sn-doped β-Ga 2 O 3 , and polycrystalline Ga-doped SnO 2 , thus realizing a p-n junction within a single HS. Factors responsible for the self-assembly of Ga 2 O 3 -SnO 2 HS are the different vapor pressures of Sn and Ga and different growth kinetics of Ga 2 O 3 and SnO 2 . Inhomogeneity in chemical content and structural composition correlated with distinct optical properties along the length of single HS. When diameters of these HS were less than 100 nm, Sn-doped Ga 2 O 3 sections of the HS exhibited the rarely observed orthorhombic ε-Ga 2 O 3 phase.

Betavoltaic power sources based on the conversion of radioisotope energy to electrical power are considered an appealing option for remote applications due to extended period of operation and high energy densities. However, to be competitive with other power sources, their efficiency must be increased. This can be done through optimization of the beta source and selection of the semiconductor absorber. This paper evaluates available on the market and developing wideband gap semiconductors as prospective absorbers with 3 H and 63 Ni sources. Simulation results indicate that among wide band gap materials 4H-SiC and diamond are two optimal semiconductors due to the combination of good coupling efficiencies with isotope sources and good electronic transport properties. Additionally, having good coupling efficiency, an ultra-wide bandgap, and the capability for both n- and p-type doping, c-BN is a promising material for betavoltaic applications.