Etching study of dislocations in heavily nitrogen doped SiC crystals

Experimental verification of the model by Klapper for 4H-SiC homoepitaxy on vicinal substrates

“…TED II and TED III dislocations are interpreted having an a-type Burgers vectorb and a line vectorl inclined from the c-direction by several degrees, i.e., they are mixed-type dislocations with a large edge component. If they lie on pyramidal glide planes f1 101g, the angle h between the h0001i direction and line vectorl amounts to 14.8 , which is in reasonable agreement to the angle of 20 reported by Wu 8 and Chung et al…”

“…[4][5][6] It has been reported that converted BPDs, i.e., TEDs in the epilayer, can be inclined about 20 from the crystallographic c-direction of the crystal. 7,8 Such inclined TEDs are also known as TED II and TED III dislocations and can be identified based on their visibility in x-ray topographs. 9 Although the BPD conversion mechanism is not fully understood on the microscopic level, 7 a pertinent model explains the behavior of dislocations at the growth interface based on dislocation energetics.…”

“…According to the model by Klapper, the minimization of the dislocation line energy at the growth interface is the driving force for BPD conversion in 4H-SiC homoepitaxial growth on vicinal substrates. It has been shown 5 that the driving force for BPD conversion becomes much stronger for decreasing off-cut angle a of the vicinal substrate, resulting in lower BPD densities of epilayers grown on 4 off-cut substrates compared to epilayers grown on 8 off-cut substrates. It has also been proven 6,14,15 that epilayers free of BPDs can be grown on defect selectively etched substrates, which means that a local on-axis condition is provided to BPDs within the vicinity of BPD etch pits.…”

Threading dislocations in n- and p-type 4H–SiC material analyzed by etching and synchrotron X-ray topography

“…Therefore, several publications (see [6] for details) report about TEDs and TSDs that are believed to be decorated by small and large hexagonally shaped etch pits, respectively. However, these dislocations may also be characterized by roundish etch pits with different sizes under certain conditions [6,7]. Wu [7] and Wu et al [8] recently reported that TEDs and TSDs cannot be distinguished explicitly in case of N-doped substrates with doping level n 45 Â 10 18 cm À 3 , as the etch pits lack a specific shape and size distribution.…”

Challenges to graphene growth on SiC(0 0 01‾): Substrate effects, hydrogen etching and growth ambient

“…Nomarski images of the surface following this etch reveal small features on the surface, which were identified by AFM as pits ( Fig. 1b and c), and are attributed to the fast etching of TSDs that intersect the surface [26,32]. For C-face graphene growth, these pits have been attributed to formation of nano-crystalline graphene during subsequent graphene growth, so these etch conditions were not used [25].…”