Links Between Etching Grooves Of Partial Dislocations And Their Characteristics Determined By TEM In 4H SiC
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Links Between Etching Grooves Of Partial Dislocations And Their Characteristics Determined By TEM In 4H SiC Jean-Pierre Ayoub, Michael Texier, Gabrielle Regula, Bernard Pichaud, and Maryse Lancin IM2NP, CNRS, Aix-Marseille Université, av. Escadrille Normandie Niemen, Marseille, 13397, France ABSTRACT We introduce defects into (112 0) oriented highly N-doped 4H-SiC by surface scratching, bending and annealing in the brittle regime. Emerging defects at the sample surface are revealed by chemical etching of the deformed samples. The etch patterns are constituted of straight bulges and grooves exhibiting various topographical features. These etch figures correspond to the emergence of double stacking faults dragged by a pair of partial dislocations. In this paper, we discuss the links between the etch figure characteristics and the defect nature. Results obtained by optical and atomic force microscopy are completed by structural analysis of defects performed by transmission electron microscopy. Mobility of partial dislocations in 4H-SiC is discussed and correlated to their core composition and to the effect of the applied mechanical stress. INTRODUCTION The exceptional properties of SiC which is both a ceramic and a wide band gap semiconductor have stimulated the rapid development of growth techniques of single-crystal, single-polytype 4H and 6H-SiC. As a result, commercial wafers of excellent crystalline perfection and controlled purity are now available. However, the performances of SiC based electronic devices are controlled by the long range defects –dislocations or stacking faults- which may develop during manufacturing. Despite numerous studies, their nucleation and propagation mechanisms are still matter of concern. So far, the dislocation dynamics was indirectly determined by plasticity experiments [1-5]. As expected, the plasticity mechanisms involve dissociated perfect dislocations above the brittle-ductile temperature and partial dislocations (PD) dragging stacking faults (SF) below. However, the multiplicity of the created SFs in N-doped 4H-SiC is a matter of debate. Pirouz and co-workers have found single SFs and multiple SFs after indentation or compression tests [1,6-7]. By surface grinding and annealing at 1100°C, Skowronski and co-workers have only created double SFs (DSF), that are faults created by two PDs gliding in two adjacent glide planes [8]. Similarly, in samples strained by cantilever bending at 550°C and 700°C after surface scratching, we only observed DSFs [9]. Recently, Mussi et al. have found SFs of various multiplicities after uniaxial compression tests [10]. The results are also controversial concerning the core composition of the leading PDs. In 4H, 6H and 3C-SiC, Pirouz and co-workers have shown that the leading PDs have always a silicon core [1,3]. In good agreement with these authors, we have shown that in 4H-SiC all the leading PDs have a silicon core whereas C-core PDs are created but are not mobile at such temperatures [9,11]. Mussi et al. on the contrary, have found b
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