Electrical, CL, EPR and RBS study of annealed SiC implanted with Al or Al and C

Abstract

Lightly n-doped, 4H-SiC films implanted with 1020 cm−3 Al or co-implanted with 1020 cm−3 Al and 1020 cm−3 C were examined in the unannealed state or annealed at 1300, 1400, 1500, 1600 or 1650 °C after they had been coated with an AlN cap. For a given annealing temperature, TA, the sheet resistance, Rsh, is smaller in the co-implanted samples at the lower TA's, but not at the higher ones because the C catalyzes the chemical reactions for the incorporation of Al into a Si site, and at the higher TA's the activation energies for these reactions no longer control the reaction kinetics. The CL peak created by a free electron recombining with a hole bound to an Al acceptor decreases in intensity as TA increases because the Al acceptors can be trapped by the deep donors related to the DI defect that increase in number as TA increases. However, the process must be more complicated because the temperature dependence of Rsh implies that the activation energy for conduction is much less than that of the 0.35 eV hole trap. The excellent temperature stability of the DI defect suggests it is likely to be associated with defects that nucleate and grow such as dislocation loops and/or stacking faults. This is consistent with decreased ion beam channeling at the higher TA's, and the small anisotropy of the EPR peak associated with implant damage. The higher energy peak in the DI doublet increases in intensity relative to the lower energy peak as TA increases, and for the same TA the relative intensity of the higher energy peak is larger in the co-implanted samples. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)