Z1/2 defect centers were produced by irradiating 4H-SiC bulk samples with 1 MeV electrons at room temperature. The emission rate dependence on the electric field in the depletion region was measured using deep level transient spectroscopy and double-correlation deep level transient spectroscopy. It is found that the Z1/2 defect level shows a strong electric field dependence with activation energy decreasing from Ec−0.72 eV at zero field to Ec−0.47 eV at 6.91×105 V/cm. The phonon assisted tunneling model of Karpus and Perel [Sov. Phys. JETP 64, 1376 (1986) ] completely describes the experimental data. This model describes the dependence of the emission rate on electric field F as en(F) = eno exp(F2/Fc2), where Fc is the characteristic field that depends on the phonon assisted tunneling time τ2. The values of Fc and τ2 were determined and the analysis of the data leads to the suggestion that Z1/2 may be a substitutional point defect.
Evwaraye, A. O.,
Smith, S. R.,
Mitchel, W. C.,
& Farlow, G. C.
(2009). Electric Field Enhancement of Electron Emission Rates from Z(1/2) Centers in 4H-SiC. Journal of Applied Physics, 106 (6), 63702.