We investigate theoretically the influence of type and density of background carriers in the active region on the quantum efficiency of InGaN-based light emitters using an extension of the ABC rate model. A method to determine experimentally whether a certain type of Auger recombination is relevant in InGaN quantum wells is derived from these considerations. Using this approach, we show that the physical process which is the dominant cause for the efficiency droop is superlinear in the electron density and can thus be assigned to nnp-Auger recombination.

Fe-implanted n-/p-type 4H-SiC samples were investigated by deep level transient spectroscopy (DLTS). In order to be able to separate Fe-related defect centers from defects caused by implantation damage, a corresponding Ar-profile was implanted. No Fe-related defects were observed in n-type 4H-SiC, while two Fe-related centers could be identified in p-type 4H-SiC. The electrical behavior of these centers is donor-like.