UV scanning photoluminescence spectroscopy applied to silicon carbide characterisation J.M. Bluet *, L. Masarotto, I. El Harrouni, G. Guillot Laboratoire de Physique de la Matie `re, CNRS (UMR5511), INSA de Lyon, Domaine Scientifique de la Doua, Ba ˆtiment Blaise Pascal 7, avenue Jean Capelle, 69621 Villeurbanne Cedex, France Abstract An UV scanning photoluminescence (SPL) equipment has been developed in order to study both structural defects at a microscopic scale and the homogeneity of physical properties at the wafer scale in silicon carbide. In one hand, the optical signature of micropipes, screw dislocation and triangular defects are presented. In most of the cases the SPL signal decrease for micropipes because of the defect geometry. In the case of dislocation, a signal exhaust in the neighbourhood of the defect is observed and attributed to the gettering effect of non radiative traps at the immediate vicinity of the defect. For triangular defects, we tentatively ascribe the PL spectra observed to Shockley stacking faults. In the other hand, a method to obtain the minority carrier lifetime mapping from the integrated PL signal is described. The mapping of this parameter is of prime interest both for the material quality control and for bipolar device’s development. # 2003 Elsevier B.V. All rights reserved. Keywords: Silicon carbide; Scanning photoluminescence; Dislocation; Micropipes; Triangular defects; Minority carrier lifetime 1. Introduction In spite of great progress in SiC growth, the rise of high performance reliable devices is still limited by the presence of microscopic structural defects and by the inhomogeneity of electrical parameters like the doping level or the minority carrier lifetime. To analyse both the defects at the microscopic scale in order to understand their origin and their impact on devices performance, and the homogeneity of electrical properties at the wafer scale, non destructive and few time consuming char- acterisation tools are strongly needed. For such a tight quality control of SiC substrates and epitaxy, we have developed a scanning photoluminescence (SPL) appara- tus, working with deep UV excitation. In our equip- ment, the PL imaging is obtained by scanning the sample fixed to an x  /y stage with 1 mm minimal step. The excitation is provided by a doubled Ar  laser beam (244 nm) focused by an achromatic microscope objective ( /52). With this excitation the spot diameter is about 2 mm and the penetration depth is below 1 mm in 4H  /SiC. Nevertheless, one must keep in mind that the diffusion length of photoexcited carriers can be much larger. The PL signal can be either directly collected, giving integrated PL intensity, either dispersed using a mono- chromator, giving spectrally resolved PL (1 nm of spectral resolution in the 300  /800 nm range). The goal of this equipment is to provide both microscopic information about structural defects in localised zones, and macroscopic mapping of physical properties homo- geneity (doping level, surface recombination velocity, minority carrier lifetime) on a whole wafer. The paper is composed of two different parts. The first one is dedicated to the analysis of microscopic structural defects, and the second one to the mapping of minority carrier lifetime on a whole wafer from the integrated photoluminescence intensity. 2. Microscopic defects analysis The most well known defects in SiC are micropipes which can be described as huge hollow core screw dislocation crossing all the sample in the [0001] direc- * Corresponding author. Tel.:  /33-4-72-438732; fax:  /33-4-72- 438531. E-mail address: bluet@insa-lyon.fr (J.M. Bluet). Materials Science and Engineering B102 (2003) 277  /283 www.elsevier.com/locate/mseb 0921-5107/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0921-5107(02)00717-1