BSI 20/30349837 DC 2020

This document specifies the testing method to determine the polytypes and their ratio in silicon carbide (SiC) wafers or bulk crystals using ultraviolet photoluminescence (UVPL) image test method. The range of SiC is limited to semiconductor SiC into which nitrogen and boron are doped to have the deep acceptor level and the shallow donor level, respectively. The SiC wafers or bulk crystals in this document typically show electrical resistivities ranging 10-2 ~ 10-3 ohm- cm, applicable to power electronic devices.

SiC to which this method is applicable: The silicon carbide (SiC) crystal of 4H, 6H and 15R polytypes, containing boron and nitrogen as acceptor and donor, respectively, at the concentrations generating Donor-Acceptor pairs to cause the UVPL . The boron and nitrogen concentration are typically 1016 and 1018 cm-3 order, respectively, in 4H SiC. When the sample is an epitaxial wafer, it should have the epitaxial layer thickness sufficiently larger than the laser penetration depth, in addition to having the boron and nitrogen dopants at the necessary concentrations. Semi-insulating SiC is not applicable, because it usually contains quite little boron and nitrogen for achieving the very high electrical resistivity.