Electrical and optical investigation of the position of vanadium related defects in the 4H and 6H SiC bandgaps

Abstract

AbstractHall effect, deep level transient spectroscopy, optical absorption, and optical admittance spectroscopy were employed to determine the position of the vanadium acceptor and vanadiumnitrogen complex in vanadium- and nitrogen-doped 4H and 6H SiC. Hall effect results indicate that the acceptor position in 4H(6H) SiC is 0.80(0.66) eV beneath the conduction band edge. The DLTS signature of the defect in the 4H polytype showed an ionization energy of 806 meV and a capture cross section of 1.8×10−16 cmr−2 The optical absorption measurements proved that the acceptor level investigated is related to isolated vanadium, and therefore the vanadium acceptor level. Based upon DLTS and SIMS measurements, the maximum solubility of vanadium in SiC was determined to the 3×10−17 crn3. An examination of polarized light experiments indicates that vanadium also complexes with another element to form electronic(at 5000 cm−1) and vibrational absorption(at 683 cm−1) bands. While the other constituent cannot be identified, evidence suggests that nitrogen is a likely candidate. This complex introduces a deep level at Ec−0.78 eV as determined using optical admittance spectroscopy.