The Impact of Surface Defects on SiC Schottky and Ohmic Contact Formation
Silicon carbide is a leading semiconductor for high power, high temperature electronics, yet SiC devices still face problems of electrical contact control and reproducibility. Recent work worldwide shows that point and extended defects in SiC as well as chemical reactions at metal-SiC interfaces can influence contact transport properties. Yet Schottky barrier and ohmic contact formation at the intimate metal-SiC junction are relatively unexplored on the microscopic level. We have used depth-resolved cathodoluminescence spectroscopy (DRCLS) and Auger electron spectroscopy (AES) to measure the optical emissions of defects near 4H-SiC surfaces and metallized interfaces on a nanometer scale. These techniques reveal that a variety of metals on clean 4H-SiC surfaces in ultrahigh vacuum (UHV) promote the formation of mid-gap defects extending only nanometers away from the junction. These states vary in their ranges of depth and depend sensitively on interface reactivity and subsequent UHV annealing
Recombination-enhanced extension of stacking faults in 4H-SiC p-i-n diodes under forward bias
The extension of stacking faults in a forward-biased 4H-SiC PiN diodes by the recombination-enhanced motion of leading partial dislocations has been investigated by the technique of optical emission microscopy. From the temperature dependence of the measured velocity of the partials, an activation energy of 0.27 eV is obtained. Based on this and analysis of the emission spectra, a radiative recombination level of 2.8 eV for the stacking fault, and two energy levels for the partial dislocation, a radiative one at 1.8 eV and a nonradiative at 2.2 eV, have been determined.
Energy
Energy is often defined as the ability to do work. There are many forms of energy. A few examples include; Gravitational energy, Kinetic energy (energy of motion), Thermal energy (heat energy), Potential energy. Potential energy is the energy something has based on its position in the universe. A stretched elastic band has potential energy. A rock held up in the air has potential energy based on its position.