Characterization of deep levels in n-type and semi-insulating 4H-SiC epitaxial layers by thermally stimulated current spectroscopy

Abstract

We have investigated deep level centers in n-type and semi-insulating (SI) 4H-SiC epitaxial layers by thermally stimulated current (TSC) spectroscopy. The epitaxial layers were grown using chemical vapor deposition utilizing a dichlorosilane precursor. Both epitaxial layers exhibited relatively shallow levels related to Al, B, L- and D-centers. A deep level center with an activation energy of 1.1 eV, peaked at ∼400 K, was detected in the n-type epitaxial layer and correlated with the IL2 level and the 1.1 eV center in a high purity bulk SI 4H-SiC. The TSC spectra of the SI epitaxial layer was dominated by the peaks at 525–585 K that we attributed to intrinsic defects and their complexes with energy levels close to the middle of the bandgap. The TSC spectra of SI epitaxial layer exhibited peaks with different current polarity which is explained by thermoelectric effect and the built-in electric field reversal. The results of the transfer length method measurements of the SI epitaxial layer and the room temperature current-voltage (I-V) characteristics of both epitaxial layers are also reported.

Advances in High-Resolution Radiation Detection Using 4H-SiC Epitaxial Layer Devices

“…Figure 16 shows an EBIC image of an n-type 4H-SiC epitaxial layer. The typical signatures of threading dislocation type defects could be seen as black spots [55,56]. The EBIC features were mapped on to the morphological defect images and it was correlated that the dark spots are the signatures of the comet tail morphological defects in the n-type epitaxial layers.…”

“…Thermally stimulated current measurement is yet another sensitive technique to study defects in semi-insulating (SI) as well as conducting samples. Figure 17 shows TSC spectra obtained from an n-type 4H-SiC epitaxial layer reverse biased at two different voltages, 4 and 12 V [56]. The spectra were acquired with a heating rate of 15 K/min.…”

Highly sensitive x-ray detectors in the low-energy range on n-type 4H-SiC epitaxial layers

“…We associate this peak with relatively shallow acceptor-like levels near the valence band edge related to Al and/or B as well as to their complexes with intrinsic defects. 6 The intensity of this peak and peaks #2 and #4 clearly shows voltage dependence of the peak intensity, implying that the deep level centers are evenly distributed in the depletion region. The intensity of peaks #3 and #5 do not show voltage dependence of the peak intensity as evidenced by inset in Fig.…”

Design, Fabrication, Characterization, and Evaluation of X-ray Detectors Based on n-type 4H-SiC Epitaxial Layer

“…The spectrum is dominated by peak #1 with maximum temperature T m = 108 K and activation energy ~ 0.25 eV estimated from Arrhenius plot (not shown). We associate this peak with relatively shallow acceptor-like levels near the valence band edge related to Al and/or B as well as to their complexes with intrinsic defects (7). Precise determination of activation energies for peaks #3 -#5 was altered by the very weak TSC from these traps (comparable to the stray current) and low signal-to-noise ratio.…”