Papers by Keyword: a-Plane

Abstract: The expansion behavior of basal plane dislocations (BPDs) in a 4H-SiC epitaxial layer on the (110) A-plane under electron beam (EB) (//[110]) irradiation was observed. BPD expanded and formed a single Shockley stacking fault (SSSF) between a partial dislocation (PD) pair. The width of the SSSF was proportional to the EB current. The dependence of the expansion velocity on the irradiation position was observed with a fixed EB spot. It was found that the electron-hole pair migration to the PD and/or SSSF can expand the SSSF. The velocity of SSSF expansion by direct SSSF excitation with an EB was much smaller than that by the preferential excitation of a PD with migrated electron-hole pairs.

Abstract: Lateral expansion of small mixed polytype 4H/6H-SiC and 6H-SiC slivers were realized by hot wall chemical vapor deposition (HWCVD). Small slivers cut from m-oriented (11 ̅00) SiC boule slices containing regions of 4H and 6H-SiC or just single polytype 6H-SiC were exposed to HWCVD conditions using standard silane/propane chemistry for a period of up to eight hours. The slivers exhibited approximately 1500 μm (1.5 mm) of total lateral expansion. Initial analysis by synchrotron white beam x-ray topography (SWBXT) confirms, that the lateral growth was homoepitaxial, matching the polytype of the respective underlying region of the seed sliver.

Abstract: We report on the fabrication and testing of SiC p-i-n avalanche photodiodes. APDs of 0.25 mm2 area on a-plane (1120) 6H-SiC as well as off-axis Si face 6H and 4H-SiC were successfully fabricated. A beveled mesa was used as edge termination. Recessed windows were formed using reactive ion etching to enhance low-wavelength UV performance. We performed current-voltage tests with and without UV illumination to determine dark current, photocurrent, and gain on selected devices. Dark current was less than 1 pA at 0.5Vbr on multiple devices. Quantum efficiency of 40% or greater was observed for all orientations and polytypes.

Abstract: In this work, avalanche photodiodes (APDs) were fabricated using a-plane 6H- and 4H-SiC materials to investigate their electrical and optical properties. Temperature dependence of avalanche breakdown was measured. The diode structures were fabricated with positive angle beveling and oxide passivation to ensure a uniform breakdown across the device area. Despite the apparent presence of micro-plasmas, we observed that the breakdown voltage of a-plane 6H-SiC APDs increased with temperature suggesting a positive temperature coefficient.