REDUCTION OF UNINTENTIONAL ALUMINUM SPIKES AT SIC VAPOR-PHASE EPITAXIAL LAYER SUBSTRATE INTERFACES

Aluminum concentrations at unintentionally doped SiC vapor phase epita xial layer/substrate interfaces were determined by secondary ion mass spectrometry to approach 1 X 10(18) cm(-3) exceeding the intentional d oping of most device active layers. Capacitance-voltage measurements i ndicate that the aluminum is electrically active resulting in compensa tion of moderately doped n-type layers. The unintentional aluminum bui ldup was successfully reduced by two orders of magnitude by minimizing exposure of the SiC substrate to propane gas prior to epitaxial growt h and by the addition of an in situ HCl etch. (C) 1996 American Instit ute of Physics.