NBN ISO 21820:2021

This document specifies a test method for determining the polytypes and their ratios in silicon carbide
(SiC) wafers or bulk crystals using ultraviolet photoluminescence (UVPL) imaging. The range of SiC is
limited to semiconductor SiC doped with nitrogen and boron to have a deep acceptor level and a shallow
donor level, respectively. The SiC wafers or bulk crystals discussed in this document typically show
electrical resistivities ranging from 10-3
ohm · cm to 10-2
ohm · cm, applicable to power electronic
devices.
This method is applicable to the SiC-crystal 4H, 6H and 15R polytypes that contain boron and nitrogen
as acceptor and donor, respectively, at concentrations that produce donor-acceptor pairs (DAPs) to
generate UVPL. In 4H-SiC the boron and nitrogen concentrations typically range from 1016
cm-3
to
1018
cm-3
. Semi-insulating SiC is not of concern because it usually contains minimal boron and nitrogen;
therefore deep level cannot be achieved.