Synchrotron topography studies of the operation of double-ended Frank–Read partial dislocation sources in 4H-SiC H. Wang a , F. Wu a , S. Byrappa a , B. Raghothamachar a,n , M. Dudley a , P. Wu b , I. Zwieback b , A. Souzis b , G. Ruland b , T. Anderson b a Department of Materials Science and Engineering, Stony Brook University, Stony Brook, NY 11794, USA b II-VI Incorporated, Wide Bandgap Materials Group, 20 Chapin Road, Suite 1007, PO Box 840, Pine Brook, NJ, USA article info Article history: Received 11 September 2013 Received in revised form 22 January 2014 Accepted 28 January 2014 Keywords: A1. Line defects A1. Planar defects A1. X-ray topography A2. Growth from vapor B2. Semiconducting silicon compounds abstract Synchrotron White Beam X-ray Topography (SWBXT) has been used to image and analyze a distinctive stacking fault pattern observed in 4H-SiC wafers. The pattern often consists of a six-pointed star comprised of multiple layers of rhombus-shaped stacking faults with three different fault vectors of the Shockley type bounded by 301 Shockley partial dislocations. Formation of this stacking fault pattern is associated with a micropipe at its center which can act as nucleation sites for dislocation half-loops belonging to the primary basal (1/3〈11 À20〉(0001)) slip system and occasionally the secondary prismatic (1/3〈11 À20〉{1 À100}) slip systems. In this case, the rhombus-shaped Shockley type stacking faults are nucleated on the basal plane by dissociation of 1/3〈11 À20〉 pure screw dislocations cross-slipped from the prismatic plane and subsequent expansion caused by glide of the leading partial and locking of the trailing partial by interaction with 601 1/3〈 À2110〉 dislocations on the basal plane. Based on these observations, a formation mechanism involving the operation of a double-ended Frank–Read partial dislocation source has been proposed. In the limit, this glide and cross-slip mechanism leads to 4H to 3C polytype transformation in the vicinity of the micropipe by a mechanism similar to that proposed by Pirouz and Yang (1993) [21]. & 2014 Elsevier B.V. All rights reserved. 1. Introduction The excellent properties of silicon carbide (SiC), a wide bandgap semiconductor, make it highly suited for electronic and optoelec- tronic devices operating under high temperature, high power, high frequency and/or strong radiation conditions [1]. However, physical vapor transport (PVT) grown commercial SiC wafers contain crystal- line imperfections such as micropipes, deformation induced basal plane dislocations (BPDs), planar defects (stacking faults, small angle boundaries), etc. that affect device performance and limit widespread application. Extensive studies have been carried out on the origins and behavior of these defects particularly using a Synchrotron white beam X-ray topography (SWBXT) [2] thereby enabling the develop- ment of strategies for eliminating or lowering their densities [3,4]. In the case of stacking faults, three types of stacking faults according to their fault vectors have been reported: the Shockley fault with fault vector of (a/3)〈1 À 100〉 type [5–7], the Frank fault with fault vector of (c/2)[0001] or (c/4)[0001] [8], and those comprising some kind of combination of the first two [9–13]. Expansion of the Shockley faults into rhombus shapes in the SiC epilayer has been shown to be associated with degradration of power devices [6]. The fault expands though a mechanism whereby the Si-core partials are electrically active, while the C-core partials are not, and the Si-core partials can couple with electron–hole recombination and move. Similarly Shock- ley faults can expand in response to applied stresses below the brittle-to-ductile transition temperature when C-core becomes ses- sile and mobile Si-core partial glides [5]. In this study, SWBXT observations of such rhombus-shaped Shockley type stacking faults on the basal plane emanating from micropipes in PVT-grown 4H-SiC wafers have been analyzed and a detailed model has been proposed to explain their nucleation. This model derives from the previously reported interaction between dislocation loops emanating from the micropipes which belong to the prismatic and basal slip systems [16]. 2. Experimental SWBXT images were recorded from PVT-grown 100 mm dia- meter 4H-SiC wafers in the transmission (1 À 100, À 1101 and 11 À 20 type reflections) and grazing incidence (11 À 28 type Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jcrysgro Journal of Crystal Growth http://dx.doi.org/10.1016/j.jcrysgro.2014.01.078 0022-0248 & 2014 Elsevier B.V. All rights reserved. n Corresponding author. E-mail addresses: balaji.raghothamachar@gmail.com (B. Raghothamachar), Michael.Dudley@stonybrook.edu (M. Dudley), pwu@ii-vi.com (P. Wu). Please cite this article as: H. Wang, et al., Journal of Crystal Growth (2014), http://dx.doi.org/10.1016/j.jcrysgro.2014.01.078i Journal of Crystal Growth ∎ (∎∎∎∎) ∎∎∎–∎∎∎