Deep Level Defects in He-implanted n-6H-SiC Studied by Deep Level Transient Spectroscopy

摘要

Deep level transient spectroscopy (DLTS) was used to study deep level defects in He-implanted n-type 6H-SiC samples. Low dose He-implantation (fluence ～2 x 10~(11) ions/cm~2) has been employed to keep the as-implanted sample conductive so that studying the introduction and the thermal evolution of the defects becomes feasible. A strong broad DLTS peak at 275K-375K (called signal B) and another deep level at E_C-0.50eV were observed in the as-implanted sample. The intensity of the peak B was observed to linearly proportional to the logarithm of the filling pulse width, which is a signature for electron capture into a defect related to dislocation. After annealing at 500℃, the intensity of peak was significantly reduced and the remained signal has properties identical to the well known Z_1/Z_2 deep defects, although it is uncertain whether the Z_1/Z_2 exist in the as-implanted sample or it is the annealing product of the dislocation-related defect. The E_1/E_2 defect (E_C-0.3/0.4eV) was not presence in the as-implanted sample, but was observed after the 300℃ annealing.