Wiley
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Influence of gas flow rates on the formation of III‐nitride nanowires Abstract This study achieved catalytic growth of gallium nitride nanowires (GaN‐NWs) and indium gallium nitride nanowires (Inx Ga1‐x N‐NWs) by the horizontal furnace chemical vapour deposition (HF‐CVD) method at the temperature of 900 °C and 550 °C, respectively. The morphologies and structures of III‐nitride nanowires depended on the gas flow rates were studied. Comparing the growth mechanisms of GaN‐NWs and Inx Ga1‐x N‐NWs, the vapour‐solid (VS) mechanism is dominant in GaN nanowires, except with a low ammonium flow rate, and the vapour‐liquid‐solid (VLS) mechanism is dominant in Inx Ga1‐x N nanowires. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wiley - Tập 7 Số 1 - Trang 40-43 - 2010
Surface properties of Al<sub>x</sub>Ga<sub>1‐x</sub>N/GaN heterostructures treated by fluorine plasma: an XPS study Abstract The variations in surface potential and the Schottky barrier height ΦB in fluorine‐plasma‐treated Alx Ga1‐x N/GaN heterotructures are systematically studied by x‐ray photoelectron spectroscopy (XPS), giving insights into the mechanisms underlying the strong threshold voltage shift in Alx Ga1‐x N/GaN HEMTs by the F plasma treatment technology. It is found that the treatment resulted in a fluorinated surface containing masses of AlF3 , with the surface potential of Al0.25 Ga0.75 N/GaN heterostructure increased by ∼0.38 eV during the first 60 seconds of the treatment. Annealing at 400 °C in N2 ambient for 10 minutes does not affect the surface potential, but results in quick reduction of AlF3 , consistent with the relative poor thermal stability of AlF3 reported in literature. ΦB between Ni and F‐plasma‐treated Al0.25 Ga0.75 N surface was extrapolated from the shift in Ga 2p 3/2 core‐level and exhibits a small increase of 0.20 eV. The enhanced ΦB is much smaller than the positive shift in Vth observed from HEMTs fabricated with the same treatment conditions, suggesting that the primary factor responsible for the conversion from depletion‐mode to enhancement‐mode Alx Ga1‐x N/GaN by F plasma treatment is not the surface modifications, but rather the negative fixed charges carried by F ions in Alx Ga1‐x N/GaN heterostructures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wiley - Tập 8 Số 7-8 - Trang 2200-2203 - 2011
Conduction and electroluminescence from organic continuous and nanofiber thin films Abstract In this work, the electrical and electroluminescence properties of para‐hexaphenylene (p6P) thin films and nanofibers have been investigated in a field‐effect transistor device configuration with interdigitated source‐drain bottom contact electrodes. P‐type behavior of thin films is observed with a mobility of 1×10‐6 cm2 /Vs and a threshold voltage around ‐30 V. AC gated devices show electroluminescence for both thin films and stamped nanofibers even when the drain electrode is floating. This suggests either hole and electron injection from the same electrode or impact ionization. The highest electroluminescence intensity is observed from thin film FETs with a 2.5 µm source‐drain gap. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wiley - Tập 7 Số 11-12 - Trang 2763-2766 - 2010
The effect of silver doping on the critical current density of Bi‐Pb‐Sr‐Ca‐Cu‐O ceramic superconductor Abstract In this research, the effect of silver doping on Bi1.6 Pb0.4 Sr2 Ca2 Cu3 Oy ceramic superconductor has been investigated. The solid‐state reaction method and two different silver doping methods has been used, namely, doping during making processes of samples (batch 1) and doping after making Bi1.6 Pb0.4 Sr2 Ca2 Cu3 Oy superconductor (batch 2). We observed that by adding silver to BPSCCO compound, partial melting temperature of the compound is decreased. The critical current density (Jc ) in both batches is affected by Ag doping. The investigation of SEM images of samples has shown that the all surfaces of the samples are porous and the grains are plate like. It seems that the BPSCCO grains in batch 1 samples are coated with silver but in the samples of batch 2, the silver also sits between the BPSCCO grains. The XRD patterns studies indicated that the silver peaks form separate phase and also by adding silver to BSCCO, the BPSCCO peaks do not show considerable shift. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wiley - Tập 3 Số 9 - Trang 2994-2998 - 2006
Zn doped GaN for single‐photon emission Abstract In this work we report on the optical investigation of Zn doped GaN films fabricated by metal organic chemical vapor deposition. The samples show bright emission in the blue spectral range around 2.9 eV when Si codoping is provided. This emission is suggested to be used for single‐photon emission, thus the density of the Zn‐Si pairs was drastically reduced leading to a decrease of the blue luminescence. For electrically excited single‐photon sources these Zn‐Si pairs have to be incorporated into LEDs, therefore we fabricated GaN‐based nano‐LEDs which show electroluminescence at 430 nm (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wiley - Tập 9 Số 3-4 - Trang 1024-1027 - 2012
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