Abstract
In this article, the thermal neutron irradiation (NI) effects on the structural properties of n-4H–SiC and electrical properties of Al/n-4H–SiC Schottky contacts have been reported. The noticeable modifications observed in the irradiated samples were studied by using different techniques. The X-ray diffraction studies revealed a decrease in the lattice parameter of the irradiated samples due to isotopic modifications and irradiation-induced defects in the material. As a result, the energy bandgap, Urbach energy, longitudinal optical phonon‒plasmon coupling mode, free carrier concentration, defect related photoluminescence and nitrogen bound exciton photoluminescence bands were prominently affected in the irradiated samples. The current–voltage characteristics of neutron irradiated Al/n-4H–SiC Schottky contacts were also strikingly affected in terms of zero-bias offset as well as decrease in the forward current. These modifications along with the increase in the Schottky junction parameters (such as ideality factor, Schottky barrier height and series resistance) were attributed to neutron-induced isotopic effects and decrease in the free carrier concentration due to induced defect states.
Highlights
In the last two decades the irradiation studies on silicon carbide (SiC), 4H–SiC polytype and its electronic devices have greatly attracted the research community
The results have shown noticeable modification in the IR transmission and Raman spectral features due to the formation of point defects
As noticed, irradiated sample have shown peak shift towards the higher side. This suggesting a decrease in the c-axis lattice constant of the material, where c can be evaluated by using the relation [18]: c= ×l, 2 sin 00l where = 1.5402 Å
Summary
In the last two decades the irradiation studies on silicon carbide (SiC), 4H–SiC polytype and its electronic devices have greatly attracted the research community. Due to superior physical properties [1] and high displacement threshold energy [2], the 4H–SiC based electronic devices [3,4,5,6,7,8,9,10] were studied and are still being examined under different irradiation environments, with different irradiation parameters as well as under different temperature conditions. The performance of such devices are known to be affected by grown-in defects, irradiation-induced defects and issues with the metal contacts. The spring loaded Al pressure contacts were used as back ohmic contacts during I‒V characterization [17]
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