Papers by Keyword: Wide Band Gap Semiconductor

Abstract: Nomarski optical microscopic, KOH etching and synchrotron topographic studies are presented of faint needle-like surface morphological features in 4H-SiC homoepitaxial layers. Grazing incidence synchrotron white beam x-ray topographs show V shaped features which transmission topographs reveal to enclose 1/4[0001] Frank-type stacking faults. Some of these V-shaped features have a tail associated with them and are referred to as Y-shaped defects. Geometric analysis of the size and shape of the V-shaped faults indicates that they are fully contained within the epilayer and appear to be nucleated at the substrate/epilayer interface. Detailed analysis shows that the positions of the V-shaped stacking faults match with the positions of c-axis threading dislocations with Burgers vectors of c or c+a in the substrate and thus appear to result from the deflection of these dislocations onto the basal plane during epilayer growth. Similarly, the Y-shaped defects match well with the substrate surface intersections of c-axis threading dislocations with Burgers vectors of c or c+a in the substrate which were deflected onto the basal plane during substrate growth. Based on the observed morphology of these defect configurations we propose a model for their formation mechanism.

Abstract: Progress in semiconductor technologies have been so consequent these last years that theoretical limits of silicon, speci cally in the eld of high power, high voltage and high temperature have been achieved. At the same time, research on other semiconductors, and es- pecially wide bandgap semiconductors have allowed to fabricate various power devices reliable and performant enough to design high e ciency level converters in order to match applications requirements. Among these wide bandgap materials, SiC is the most advanced from a techno- logical point of view: Schottky diodes are already commercially available since 2001, JFET and MOSFET will be versy soon. SiC-based switches Inverter e ciency bene ts have been quite established. Considering GaN alternative technology, its driving force was mostly blue led for optical drive or lighting. Although the GaN developments mainly focused for the last decade on optoelectronics and radio frequency, their properties were recently explored to design devices suitable for high power and high e ciency applications. As inferred from various studies, due to their superior material properties, diamond and GaN should be even better than SiC, silicon (or SOI) being already closed to its theoretical limits. Even if the diamond maturity is still far away from GaN and SiC, laboratory results are encouraging speci cally for very high voltage devices. Apart from packaging considerations, SiC, GaN and Diamond o ers a great margin of progress. The new power devices o er high voltage and low on-resistance that enable important reduction in energy consumption in nal applications. Applications for wide bandgap materials are the direction of high voltage but also high temperature. As for silicon technology, WBG-ICs are under development to take full bene ts of power and drive integration for high temperature applications.

Abstract: In this paper, we extend the super junction concept to SiC high voltage devices and further expand the SiC theoretical limit. It is shown that the super-junction concept can reduce the theoretical specific on-resistance by several times to several orders of magnitude for both silicon and SiC. The unique merit of SiC super-junction devices is that the required P and N pillars have a much smaller aspect ratio and may be easier to form than their silicon counterparts. Furthermore, SiC super-junction devices are much less sensitive to charge imbalance issue than silicon SJ devices.

Abstract: Diamond layers have a potential application as the highest band-gap semiconductor for electronic devices. One of the major problems is to form electric contact on the diamond surface useful for an electronic device. This paper shows the properties of the contacts formed by the very promising ion implantation technique. The diamond layers were deposited with Microwave Assisted Chemical Vapor Deposition (MW-CVD) equipped with special extra features like High Voltage Bias and Heated Substrate Holder [1]. Phosphoruos ion implantation and gold deposition were used for the contact formation. This technique resulted graphitization the top of the diamond film and intermixing of gold with the graphite or diamond surface. The properties of the contacts were tested with surface conduction characterization methods, and the properties of the contact to diamond interface was investigated with SIMS (Secondary Ion Mass Spectroscopy ) and XPS (X-ray Photoelectron Spectroscopy).