Synthesis of GdB6 nanostructures using nanosecond (Nd: YAG) laser: field emission investigation
We herein report field emission characteristics of GdB6 nanostructures grown directly on a pellet via laser processing (laser fluence ~ 6 J/cm2). The laser processed GdB6 pellet was characterized by X-ray diffraction, which revealed no change in phase upon laser processing. The values of the turn-on field required to draw emission current density of 1 μA/cm2 is found to be ~ 2.95 V/μm, for the laser processed GdB6 emitter. Furthermore, the Fowler-Nordheim (F-N) plot exhibits nonlinear behavior over the entire range of applied field and the field enhancement factor (β) calculated from slope of the F-N plot (low field region) was found to be ~ 543. The emission current stability over a period of 3h was observed to be fairly good. The observed results demonstrate that laser processing can be efficiently used to make GdB6 nanostructure emitter having potential for practical applications.
Single-crystalline GdB6 nanowire field emitters.
Having the lowest work function in the rare-earth hexaboride family, GdB6 nanowires of rectangular cross-section with about 50 nm in lateral dimension and several microns in length have been successfully produced using a CVD method. The nanowires are grown in the 001 lattice direction, and both the tip-top and the side surfaces are terminated with the {100} lattice planes. A GdB6 single nanowire field emitter has also been built with an emission current of more than 150 nA at an applied field of less than 3.2 V/mum. The work function of the nanowire emitter was estimated to be about 1.5 eV.
Photoreflectance characterization of vanadium-doped GaAs layers grown by metalorganic vapor phase epitaxy
Abstract We characterized the vanadium-doped (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy. The conductivity of the samples is checked by the Hall effect measurements, and it is n type with electrons concentration ranging from 2×10 13 to 2×10 17  cm −3 . We used the photoreflectance technique (PR) to study the effect of vanadium doping on the optical properties of GaAs. Our experimental results show that the built-in electric field F and the broadening parameter Γ 0 increase with V-doping concentration. Furthermore, the temperature dependence of the built-in electric field and the broadening parameter of GaAs:V samples have been investigated by PR. It has been observed that these parameters increase with increasing temperature. The decrease of the built-in electric field with decreasing temperature is due to the photovoltage effect.We characterized the vanadium-doped GaAs (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy.