Thermally stimulated current and high temperature resistivity measurements of 4H semi-insulating silicon carbide

High purity semi-insulating 4H SiC single crystals have potential applications for room temperature radiation detectors because of the wide band gap and radiation hardness. To control carrier lifetime, a key parameter for high performance radiation detectors, it is important to understand the nature of the deep traps in this material. For this purpose, we have successfully applied thermally stimulated current (TSC) and high temperature resistivity measurements to investigate deep level centers in semi-insulating 4H SiC samples grown by physical vapor transport. High temperature resistivity measurements showed that the resistivity at elevated temperatures is controlled by the deep level with an activation energy of 1.56 eV. The dominant traps revealed by TSC measurements were at 1.1–1.2 eV. The deep trap levels in 4H-SiC samples, the impurity and point defect nature of TSC traps peaked at ∼106 K (0.23 eV), ∼126 K (0.32 eV), ∼370 K (0.95 eV), ∼456 K (1.1–1.2 eV) are discussed.

Research highlights
► Characterized deep energy levels in semi insulating 4H SiC.
► Deep centers with activation energies of 0.23, 0.32, 0.42, 0.95, 1.1, 1.2, and 1.56 eV were found.
► Traps at 1.1–1.2 eV dominate over V center (0.95 eV).
► The resistivity was controlled by the 1.56 eV level.
► The energy levels of 1.1, 1.2 and 1.56 eV are intrinsic defects controlling the carrier lifetime.