Abstractp–n diodes were fabricated from 3C‐SiC films heteroepitaxially grown atop on‐axis, Si‐face (0001) 4H‐SiC mesa substrate arrays [P. G. Neudeck et al., Mater. Sci. Forum 433–436, 213 (2003); 527–529, 1335 (2006)]. Images taken by electroluminescence‐based optical emission microscopy (ELOEM) and electron channelling contrast imaging (ECCI) revealed immobile linear features aligned along 〈110〉 directions; defects were expected on these particular devices, as the 3C films were grown on stepped 4H mesas. To explain the formation of these defects, we have used a procedure by which surface energies are calculated for terraces on a stepped 4H, Si‐face surface to investigate their comparative stability; subsequently, we use energetic calculations to confirm the formation – and determine the orientation – of 3C nuclei on the more stable 4H terraces and to evaluate the nature of the coalescence of nuclei from neighbouring terraces. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

pn diodes have recently been fabricated from 3C-SiC material heteroepitaxially grown atop on-axis 4H-SiC mesa substrate arrays [1,2]. Using an optical emission microscope (OEM), we have investigated these diodes under forward bias, particularly including defective 3C-SiC films with in-grown stacking faults (SFs) nucleated on 4H-SiC mesas with steps from screw dislocations. Bright linear features are observed along <110> directions in electroluminescence (EL) images. These features have been further investigated using electron channeling contrast imaging (ECCI) [3]. The general characteristics of the ECCI images—together with the bright to dark contrast reversal with variations of the excitation error—strongly suggest that the bright linear features are partial dislocations bounding triangular SFs in the 3C-SiC films. However, unlike partial dislocations in 4H-SiC diodes whose recombination-enhanced dislocation motion serves to expand SF regions, all the partial dislocations we observed during the electrical stressing were immobile across a wide range of current injection levels (1 to 1000 A/cm2).

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This article presents cross-sectional transmission electron microscopy and molten-potassium hydroxide etching studies of (111) 3C-SiC diodes which we previously reported to be free of forward-voltage drift despite abundant electroluminescent linear features presumed to be defects. Our results show that the majority of linear features are stacking faults lying in inclined {111} planes. Additionally, high densities of isolated etch pits (10 6 -10 8 cm -2 ) are observed in 3C films grown on stepped 4H mesas, while 3C films nucleated on step-free 4H mesas exhibited orders of magnitude fewer etch pits and stacking faults. Defect formation mechanisms whose impetuses are steps on the 4H-SiC pregrowth mesa are discussed.