Polytype switching identification in 4H-SiC single crystal grown by PVT
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Polytype switching identification in 4H‑SiC single crystal grown by PVT Aman Arora1 · Akhilesh Pandey1 · Ankit Patel1 · Sandeep Dalal1 · Brajesh S. Yadav1 · Anshu Goyal1 · R. Raman1 · O. P. Thakur1 · Renu Tyagi1 Received: 26 June 2020 / Accepted: 5 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Generally, it is very difficult to grow large diameter 4H-SiC single crystal with single polytype by Physical Vapor Transport (PVT) growth method and mostly it ends up with the presence of some other polytypes (viz. 6H, 15R). This paper presents the various comprehensive polytype identification techniques in SiC wafer grown by PVT method. Characterization techniques, viz. X-Ray diffraction, Scanning electron microscopy, Cathodoluminescence (CL) and Raman spectroscopy, are used in the present study in order to identify the presence of 4H, 6H and 15R polytype region in SiC wafer. Raman mapping (using phonon frequencies at 150, 171, 203 c m−1 for 6H, 15R and 4H, respectively) and X-Ray Topography [using grazing incidence asymmetric plane (11–2 8) for 4H-SiC, (11–2 12) for 6H-SiC and (11–2 30) for 15H-SiC] and CL spectra (defect state peak positions at ~ 500 nm and 580 nm for 4H and 6H, respectively) are proposed to distinguish the switching of polytypes in a large area SiC wafer. The polytype switching in SiC ingot may occur because of temperature fluctuations during the sublimation growth process.
1 Introduction Since the last two decades, wide bandgap semiconductors significantly became an important material in the various electronics and optoelectronics applications worldwide [1]. The main reason for their popularity may be due to the capability of devices fabricated from these materials to withstand high operating temperatures, high power levels and harsh environmental conditions [1–4]. SiC possesses good thermal conductivity, high breakdown field, high stability and many other important properties [2–4]. Since it exhibits a wide bandgap and high electron saturation velocity, it can sustain a high electrical breakdown field and can be used in high-frequency devices. Due to high thermal conductivity, SiC-based MEMS devices are widely used in various military and space applications [5]. Devices using SiC materials like high switching devices, bipolar electronic devices [6], and substrates for GaN-based device structure for high-frequency and high-power devices [7, 8] are other prominent applications of SiC. SiC materials play an important role
* Akhilesh Pandey [email protected] 1
Solid State Physics Laboratory, DRDO, Lucknow Road, Timarpur, Delhi 110054, India
in automotive, spacecraft, aircraft and defence equipment (tank, engine, etc.) [9]. More than 200 polytypes of SiC materials exist in nature and it exhibits different characteristics in terms of physical properties [10]. Ample literature already exists related to SiC polytypism [10–13]. Researchers discussed the various SiC polytype (3C, 4H, 6H, 15R) formation from the perspective of thermodynamics [11, 12]
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