Search results for "Annealing"
showing 4 items of 434 documents
Effects of Excimer Laser Irradiation on the Morphological, Structural, and Electrical Properties of Aluminum-Implanted Silicon Carbide (4H-SiC)
2022
This paper reports on the effects of excimer laser irradiation on an aluminum (Al)-doped silicon carbide (4H-SiC) layer. Specifically, high-concentration (1 × 1020at/cm3) Al-implanted 4H-SiC samples were exposed to a few pulses of 308 nm laser radiation (pulse duration of 160 ns), with fluence varying from 1.0 to 2.8 J/cm2. As a starting point, the laser-induced modifications of the morphological, microstructural, and nanoelectrical properties of the exposed 4H-SiC surface were monitored by combining different techniques. From these investigations, an evolution of the surface morphology was observed that can be ascribed to a conversion during irradiation of the uppermost part of the 4H-SiC …
Charge Transport Mechanisms in Heavy-Ion Driven Leakage Current in Silicon Carbide Schottky Power Diodes
2016
Under heavy-ion exposure at sufficiently high reverse bias voltages silicon carbide (SiC) Schottky diodes are observed to exhibit gradual increases in leakage current with increasing ion fluence. Heavy-ion exposure alters the overall reverse current-voltage characteristics of these diodes, leaving the forward characteristics practically unchanged. This paper discusses the charge transport mechanisms in the heavy-ion damaged SiC Schottky diodes. A macro model, describing the reverse current-voltage characteristics in the degraded SiC Schottky diodes is proposed. peerReviewed
Effect of thermal annealing on the luminescence of defective ZnO nanoparticles synthesized by pulsed laser ablation in water
2016
This work concerns ZnO nanoparticles (NPs), with sizes of tens of nm, produced by ablation with a pulsed Nd:YAG laser of a Zn plate in H2O. TEM images evidence the formation of nanoparticles with sizes of tens of nm. Moreover, HRTEM images and Raman spectra show that the distance between the crystalline planes and the vibrational modes are consistent with ZnO nanocrystal in wurtzite structure. Their optical properties are characterized by two emission bands both excited above the energy gap (3.4 eV): the first at 3.3 eV is associated with excitons recombination, the second at 2.2 eV is proposed to originate from a singly ionized oxygen vacancy. The green emission is independent of water pH,…
Applications of tunnel junctions in low-dimensional nanostructures
2009
This thesis concentrates on studies of AlOx based tunnel junctions and their feasibility for cooling, thermometry and strain sensing in suspended nanostructures. The main result of the thesis is cooling of one dimensional phonon modes of a suspended nanowire with normal metal insulator superconductor (NIS) tunnel junctions. Simultaneous cooling of both electrons and phonons was achieved, and the lowest phonon temperature reached in the system was 42 mK with an initial temperature of 100 mK. In addition, suspended devices show cooling still at a bath temperature of 600 mK. The observed thermal transport characteristics show, that the heat flow is limited by the scattering of phonons at the b…