Photothermal ionization spectroscopy of shallow nitrogen donor states in 4H-SiC

Citation
Cq. Chen et al., Photothermal ionization spectroscopy of shallow nitrogen donor states in 4H-SiC, J APPL PHYS, 87(8), 2000, pp. 3800-3805
Citations number
34
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF APPLIED PHYSICS
ISSN journal
0021-8979 → ACNP
Volume
87
Issue
8
Year of publication
2000
Pages
3800 - 3805
Database
ISI
SICI code
0021-8979(20000415)87:8<3800:PISOSN>2.0.ZU;2-U
Abstract
Photothermal ionization spectroscopy (PTIS) measurements were carried out o n a free-standing, high purity and high quality 4H-SiC epitaxial layer at v arious temperatures. The two step photothermal ionization process is clearl y reflected in the temperature dependence of the photoconductivity. The PTI spectrum at a temperature of 25.6 K exhibits one order of magnitude higher energy resolution than the infrared absorption spectra of 4H-SiC bulk mate rial. It reveals five strong, well resolved electronic transition lines ass ociated with the shallow nitrogen donor. The ionization energy of the shall ow nitrogen donor is deduced to be 60.2 +/- 0.5 meV based on experimental r esults. Furthermore, PTI magnetospectroscopy measurements were performed to investigate the symmetry properties of these transitions in Faraday config uration. No linear Zeeman splitting is observed, however, these lines show a diamagnetic shift. It indicates that the excited states of the shallow ni trogen donor are nondegenerate at zero magnetic field, which is consistent with the fact that the effective mass tensor of 4H-SiC has three different diagonal components. (C) 2000 American Institute of Physics. [S0021-8979(00 )00208-5].