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Full-Text Articles in Physics
A New Silicon Phase With Direct Band Gap And Novel Optoelectronic Properties, Yaguang Guo, Qian Wang, Yoshiyuki Kawazoe, Puru Jena
A New Silicon Phase With Direct Band Gap And Novel Optoelectronic Properties, Yaguang Guo, Qian Wang, Yoshiyuki Kawazoe, Puru Jena
Physics Publications
Due to the compatibility with the well-developed Si-based semiconductor industry, there is considerable interest in developing silicon structures with direct energy band gaps for effective sunlight harvesting. In this paper, using silicon triangles as the building block, we propose a new silicon allotrope with a direct band gap of 0.61 eV, which is dynamically, thermally and mechanically stable. Symmetry group analysis further suggests that dipole transition at the direct band gap is allowed. In addition, this new allotrope displays large carrier mobility (~104 cm/V · s) at room temperature and a low mass density (1.71 g/cm3), making …
Using Graphene To Control Magnetic Anisotropy And Interaction Between Supported Clusters, Sanjubala Sahoo, M Fhokrul Islam, Shiv N. Khanna
Using Graphene To Control Magnetic Anisotropy And Interaction Between Supported Clusters, Sanjubala Sahoo, M Fhokrul Islam, Shiv N. Khanna
Physics Publications
Stabilization of magnetic order in clusters/nanoparticles at elevated temperatures is a fundamentally challenging problem. The magnetic anisotropy energy (MAE) that prevents the thermal fluctuations of the magnetization direction can be around 1–10 K in free transition metal clusters of around a dozen atoms. Here we demonstrate that a graphene support can lead to an order of magnitude enhancement in the anisotropy of supported species. Our studies show that the MAE of supported Co5 and Co13 clusters on graphene increase by factors of 2.6 and 25, respectively. The enhancement is linked to the splitting of selected electronic orbitals that leads to …
Identification Of Point Defects In Hvpe-Grown Gan By Steady-State And Time-Resolved Photoluminescence, Michael A. Reshchikov, Denis O. Demchenko, A Usikov, H Helava, Yu. Makarov
Identification Of Point Defects In Hvpe-Grown Gan By Steady-State And Time-Resolved Photoluminescence, Michael A. Reshchikov, Denis O. Demchenko, A Usikov, H Helava, Yu. Makarov
Forensic Science Publications
We have investigated point defects in GaN grown by HVPE by using steady-state and time-resolved photoluminescence (PL). Among the most common PL bands in this material are the red luminescence band with a maximum at 1.8 eV and a zero-phonon line (ZPL) at 2.36 eV (attributed to an unknown acceptor having an energy level 1.130 eV above the valence band), the blue luminescence band with a maximum at 2.9 eV (attributed to ZnGa), and the ultraviolet luminescence band with the main peak at 3.27 eV (related to an unknown shallow acceptor). In GaN with the highest quality, the dominant defect-related …
Defect-Related Luminescence In Undoped Gan Grown By Hvpe, Michael A. Reshchikov, A Usikov, H Helava, Yu. Makarov
Defect-Related Luminescence In Undoped Gan Grown By Hvpe, Michael A. Reshchikov, A Usikov, H Helava, Yu. Makarov
Forensic Science Publications
Hydride vapor phase epitaxy (HVPE) is used for the growth of low-defect GaN. We have grown undoped films on sapphire and investigated them using steady-state and time-resolved photoluminescence (PL). One of the dominant PL bands in high-quality GaN grown by HVPE is the green luminescence (GL) band with a maximum at 2.4 eV. This PL band can be easily recognized in time-resolved PL measurements due to its exponential decay even at low temperatures (<50 K), with a characteristic lifetime of 1–2 μs. As the temperature increases from 70 K to 280 K, the PL lifetime for the GL band increases by an order of magnitude. This …