Transient capacitance investigations were made of deep levels in 6H wafers which had been grown by using a modified Lely method. Several deep electron traps were detected whose concentrations were of the order of 1015/cm3 and which were located at 0.39 to 0.69eV below the conduction band edge. However, step-controlled epitaxial layers contained very few traps and their concentrations were below the detection limit of 1013/cm3.

S.Jang, T.Kimoto, H.Matsunami: Applied Physics Letters, 1994, 65[5], 581-3