Improvement of 4H-SiC material quality: Invited paper presented at the First International Symposium on SiC Spintronics, Vadstena, Sweden, June 15-17, 2015

Abstract

The Fraunhofer IISB will introduce its activities in Silicon Carbide to the spintronic community with a special focus on its undertakings on material development and characterization. Our activities in materials development started about 10 years ago. We were improving the 4H-SiC homoepitaxial growth process in order to avoid extended defects, e.g. dislocations and stacking faults, in homoepitaxial layers. We were able to avoid device-killing defects like Basal Plane Dislocations in epilayers and explained these experimental results by appropriate models. Within the last years, the improvement of the minority carrier lifetime by reducing the point defect density has come into focus. Therefore, the influence of epigrowth parameters like, e.g. gas mixing and growth temperature, on the point defect density and carrier lifetime are investigated by using Deep Level Transient Spectroscopy (DLTS) and microwave-detected photoconductivity decay (µ-PCD). Our recent developments target on the reduction of the carbon vacancy, which is known as a lifetime-killing defect. The experimental work is completed by implementing models regarding the point defect generation / annihilation as well as the carrier lifetime measurements. Besides the materials development, the Fraunhofer IISB has been manufacturing SiC electronic devices for more than 20 years. We are producing power electronic as well as optoelectronic SiC devices in small series or prototype fabrication. The process line could be used also to fabricate spintronic prototype devices. In our presentation, we will show and discuss ou r recent advances in materials development and characterization as well as introduce the device processing