Infrared absorption spectra of 4H silicon carbide

We performed infrared absorption measurements on 4H-SiC samples with polarization E∥c and E⊥c at 8, 85 and 300 K. From the strong temperature dependence of the absorption lines, electronic transitions are separated from vibronic transitions. The electronic transition lines between 300 and 500 cm^-1 are assigned to the shallow nitrogen donor. It is found that the electronic transitions of the shallow nitrogen donor are polarization dependent. Zeeman spectroscopy was performed to study the influence of the magnetic field on the electronic transitions up to 15 T. The results show no linear Zeeman splitting and only a diamagnetic shift. This is consistent with the effective mass tensor of three different diagonal components in 4H-SiC. Received: 25 November 1999 / Accepted: 20 April 2000 / Published online: 2 August 2000