We present investigation of carrier transport and trapping in 4H-SiC single crystals and high-energy radiation detectors. SiC detectors were produced from bulk vanadium-compensated semi-insulating single crystal 4H-SiC and provided with nickel ohmic and titanium Schottky contacts. The prevailing defect levels were revealed by means of thermally stimulated current and thermally stimulated depolarization methods and their advanced modification — multiple heating technique. From I−V measurements a Schottky barrier height of ≈ 1.9 eV was found. In 4H-SiC:Va the following thermal activation values were deduced: 0.18–0.19 eV, 0.20–0.22 eV, 0.3–0.32 eV, 0.33–0.41 eV, and 0.63 eV. The maximum with activation energy of 0.33–0.41 eV appears below 125 K and most probably is caused by thermal carrier generation from defect levels. In contrast, the first three maxima with lowest activation energies, which appear at higher temperatures, are likely associated with material inhomogeneities causing potential fluctuations of the band gap. The existence of different polarization sources in different temperature ranges is also demonstrated by thermally stimulated depolarization.
[1]
S. Maximenko,et al.
Electron-beam-induced current observed for dislocations in diffused 4H-SiC P-N diodes
,
2004
.
[2]
M. Rahman,et al.
Performance of irradiated bulk SiC detectors
,
2003
.
[3]
L. Pintilie,et al.
Formation of the Z1,2 deep-level defects in 4H-SiC epitaxial layers: Evidence for nitrogen participation
,
2002
.
[4]
F. Bechstedt,et al.
Native defects and complexes in SiC
,
2001
.
[5]
I. Kityk,et al.
Photoinduced second harmonic generation in molecular crystals caused by defects
,
2001
.
[6]
K. Smith,et al.
Thermally stimulated currents in semi-insulating GaAs Schottky diodes and their simulation
,
1999
.
[7]
J. G. Simmons,et al.
High-Field Isothermal Currents and Thermally Stimulated Currents in Insulators Having Discrete Trapping Levels
,
1972
.