4H-SiC Crystals Research Articles

Study on Dislocation Behaviors during PVT Growth of 4H-SiC

The generation and transformation of dislocations in 4H-SiC crystals grown by PVT were investigated. Experiments were carried out in two stages for more comprehensive observation on dislocation behaviors. For the first stage known as initial growth, we investigated mainly the seed and grown interface. The behavior and transition of the dislocations in grown crystal were observed along the length of the crystal at second stage. The formation of threading edge dislocations (TEDs) strongly depends on the surface morphologies related with internal temperature gradients during crystal growth. The basal plane dislocation (BPDs) and threading screw dislocation (TSDs) cause from the seed crystal and formed at the initial stage of growth were gradually decreased in number along the length of the crystal and under certain conditions such as distorted stresses, dislocations were converted into other types of dislocations.

Control of temperature distribution to suppress macro-defects in solution growth of 4H-SiC crystals

We investigated the surface roughening in 4H-SiC solution growth from the following two aspects: the roughening of the seed surface before seeding and the roughening caused by the adhesion of SiC particles during growth. First, we investigated the morphological changes of the seed surface before and after the melt-back process. The seed surface just before seeding was covered with macrosteps and 6H-SiC hillocks with a height of several micrometers. This surface roughening was caused by condensation of droplets of vaporized solvent on the seed surface. We found that the 6H-SiC hillocks were the origins of trench defects. The melt-back process completely removed the hillocks and produced a smooth surface adequate for successive bulk growth. Second, we investigated surface roughening caused by the formation of SiC particles. The adhesion of SiC particles on the growth surface introduced trench defects and polytype inclusions. The adhesion of SiC particles was suppressed by controlling the distribution of carbon supersaturation in the solvent.

(Invited) Unified Understanding of the Shockley Stacking Fault Formation in 4H-SiC Crystals under Thermal Equilibrium and Non-Thermal Equilibrium Conditions Based on the Quantum Well Action Concept

The formation mechanism of Shockley stacking faults (SFs) in 4H-SiC crystals is discussed on the basis of the quantum well action concept. Theoretical investigation of the energetics of the SF formation in 4H-SiC crystals reveals the underlying physics governing the SF formation under thermal equilibrium and non-thermal equilibrium conditions. The similarity and dissimilarity of the SF formation in these two conditions are discussed, and based on it, a unified understanding of the phenomena is attempted.

Analysis of Basal Plane Dislocation Dynamics in PVT-Grown 4H-SiC Crystals during High Temperature Treatment

Fundamental understanding of the generation and multiplication of basal plane dislocations (BPDs) in PVT-grown 4H-SiC crystals is critical for design of growth strategies to control their densities during PVT growth of 4H-SiC crystals. Direct observation of thermal gradient induced motion of basal plane dislocations by in-situ synchrotron X-ray topography imaging of PVT-grown 4H-SiC wafers subject to high temperature treatment has provided an opportunity to analyze the movement of dislocations. Dislocations with Burgers vector along the off-cut [11-20] direction were found to be the only dislocations involved in deformation during heat treatment and the segments of dislocations used for velocity measurements were found to be either pure screw comprised of both Si- and C- core partials or 60° dislocations comprised of purely Si cores. Using the kink-diffusion model, the activation energies for dislocation motion have been estimated from the velocity data for each of these dislocation types and found to be 2.21 eV for 60° and 3.28 eV for pure screw segments, respectively. These values are in good agreement with the macroscopic studies of yielding of semiconductor crystals during high temperature compression and indentation experiments. Quantitative expression of the temperature dependent critical resolved shear stress required for dislocation motion has been derived from this analysis.

Relationship between Basal Plane Dislocation and Local Basal Plane Bending in PVT-Grown 4H-SiC Crystals

Synchrotron monochromatic beam x-ray topography (SMBXT) shows black and white contrast of BPDs for Burgers vectors of opposite signs based on the principle of ray tracing. We have evaluated the ratio of black and white contrast of BPDs along both [1120] and [1100] directions across multiple 4-inch and 6-inch diameter 4H-SiC substrates. Results show the predominance of white contrast BPDs along both radial directions indicating that the basal planes on Si face are bent in a convex manner. Line scans of 0004 reflection using HRXRD was carried out which further confirmed the nature of basal plane bending in these wafers. Detailed analysis on the subsequent wafers across the crystal boule reveals the inheritance of basal plane bending behavior in these wafers. The radius of curvature in 6-inch wafers was found to be larger than the 4-inch wafers. Additional studies on the effect of low angle grain boundaries were also discussed.

Strain engineering 4H-SiC with ion beams

Single crystals of 4H-SiC irradiated with 900 keV Si and 21 MeV Ni ions separately and sequentially were studied by Rutherford backscattering spectrometry in channeling geometry, single crystal X-ray diffraction, and Raman scattering. SiC irradiated with 900 keV Si ions to a fluence of 6.3 × 1014 ions/cm2 experiences 7.3% strain over the depth of 650 nm. Strain relaxation from ionization-induced annealing was directly observed due to subsequent irradiation with 21 MeV Ni ions to a fluence of 2 × 1014 ions/cm2. These competitive processes suggest the use of ion irradiation to create a specific strain state in 4H-SiC, particularly in films.

Investigation of the 6-Folded Pattern in the Facetted Region of 4° Off-Axis 4H-SiC

We demonstrate 4o off-axis 4H-SiC bulk crystal growth using physical vapor transport method (PVT). A radial 6-folded pattern is discovered in the facetted region of the growth surface by differential interference contrast microscopy. SICA88 Wafer Inspection/Review System was used to further inspect such 6-folded pattern with photoluminescence channel for wafers cut from that 4H-SiC crystal. It was found that the 6-folded pattern exists in all the wafers from the bottom to the top of that crystal. Several radial 6-folded patterns are found in the bottom wafer near the seed, but there is only one in the other two wafers. Defects distribution of these wafers after etched were also researched to find out the relationship between the radial 6-folded pattern and the defects. Based on the results, the formation and evolution mechanism of the radial 6-folded pattern on 4o off-axis 4H-SiC crystal is discussed.

Impact of intrinsic defects on excitation dependent carrier lifetime in thick 4H-SiC studied by complementing microwave photoconductivity, free-carrier absorption and time-resolved photoluminescence techniques

Photoexcited carrier dynamics in 1014–1018 cm−3 density range was investigated by using complementary optical and microwave techniques. Bulk lifetime decrease from 4 μs to 460 ns with excitation and its increase with temperature were observed in bulk n-type 4H-SiC crystal. The latter data and modeling of excitation-dependent hole capture with subsequent electron capture provided the trap position at EV + 0.19 eV and electron (hole) lifetimes of 360 ns (100 ns), correspondingly, at high excitation conditions. Lifetime increase with temperature was observed due to the trap thermal activation and reduction of electron capture cross section. The trap origin was discussed in terms of silicon vacancy related and titanium point defects. Photoluminescence spectra in 24–300 K range revealed bound exciton luminescence and nitrogen-aluminum donor-acceptor pair band, which time-resolved and excitation dependent dynamics was analyzed.

Formation and multiplication of basal plane dislocations during physical vapor transport growth of 4H-SiC crystals

The distribution of basal plane dislocations (BPDs) in physical vapor transport (PVT) grown 4H-SiC crystals has been investigated using Raman microscopy and X-ray topography. X-ray topography observations of (1 1 2¯ 0) wafers vertically sliced along the growth direction from the crystals revealed that there existed almost periodically arranged layers with a high density of BPDs (bunched BPDs) in PVT-grown 4H-SiC crystals. These layers were characterized using Raman microscopy and high resolution X-ray diffraction, and it was found that large tensile and compressive stresses were associated with the layers. The stresses showed characteristic variations along the basal plane as well as the growth direction. Based on these results, the formation and multiplication processes of BPDs during PVT growth of 4H-SiC crystals are elucidated.

Structural characterization of the grown crystal/seed interface of physical vapor transport grown 4H-SiC crystals using Raman microscopy and x-ray topography

The defect structure at and near the grown crystal/seed interface of 4H-SiC single crystals grown by the physical vapor transport (PVT) growth method has been investigated using Raman microscopy and x-ray topography. To examine the detailed distribution of crystallographic defects across the interface, 4H-SiC wafers containing a beveled growth interface were prepared from nitrogen-doped 4H-SiC single crystal boules; the beveled interface allows more spatially resolved observations of the defect structure near the interface compared to the interface on vertically sliced [e.g., (112¯0) and (11¯00)] wafers. Raman microscopy imaging using the longitudinal optical phonon-plasmon coupled (LOPC) mode determined the position of the growth interface and revealed several characteristic features of the interface through the analyses of the scattering intensity, peak position, and width of the LOPC mode peak. X-ray topography revealed that there existed networks of basal plane dislocations at the growth interface, and they extended deep inside the seed crystal. Based on these observations, we discussed the defect formation process at the initial stage of PVT growth and suggested an important role of vacancy injection during PVT growth of SiC.

Quantum well action model for the formation of a single Shockley stacking fault in a 4H-SiC crystal under non-equilibrium conditions

The formation of single Shockley stacking faults (SSSFs) in 4H-SiC crystals under non-equilibrium conditions (e.g., the forward biasing of PiN diodes and ultraviolet light illumination) is a key phenomenon in the so-called bipolar degradation of SiC power devices. This study theoretically investigated the physical mechanism of this phenomenon based on the concept of quantum well action. As a first approximation describing the non-equilibrium state of the material, we employed quasi-Fermi level approximation. We then made improvements by considering several physical effects governing the carrier distribution near and in the SSSF. The improved model accounts well for the excitation threshold and the temperature dependence of SSSF expansion. Thus, the model provides useful insights into the driving force of SSSF expansion under non-equilibrium conditions.

Studies on Lattice Strain Variation due to Nitrogen Doping by Synchrotron X-ray Contour Mapping Technique in PVT-Grown 4H-SiC Crystals

Lattice strain in 4H-SiC substrate wafers can have a deleterious effect on the performance of power electronic devices, especially under high-temperature operation. Significant strain can be introduced by lattice parameter change due to the incorporation of impurities in heavily doped 4H-SiC crystals. Synchrotron x-ray topographic contour mapping technique is able to deconvolute the lattice strain component from lattice tilt and thus generate strain maps, which has been incorporated into an anisotropic elasticity model to determine the nitrogen doping concentration in 4H-SiC substrate wafers. In order to further investigate the relationship between lattice strain and doping concentration, the lattice strain variation across the facet and off-facet regions in different 4H-SiC substrate wafers was studied. Hall effect measurements were carried out to measure the nitrogen concentration of 4H-SiC wafers, which shows a decrease in resistivity and Hall mobility with the increase of nitrogen concentration. The result shows that lattice strain within the basal plane is isotropic, while along the growth direction [0001], the strain value is one order magnitude lower. Qualitative study of lattice strain reveals more uniform distribution of strain inside the wafer facet compared to the outside regions. Additionally, wafers with higher nitrogen concentration were found to have larger overall lattice strain variation. Variation of lattice strain due to nitrogen doping was further confirmed by triple axis x-ray rocking curve measurements showing the highest full width at half maximum inside the wafer facet.

Thermal conductivity of GaN, GaN71 , and SiC from 150 K to 850 K

The thermal conductivity (\ensuremath{\Lambda}) of wide-band-gap semiconductors GaN and SiC is critical for their application in power devices and optoelectronics. Here, we report time-domain thermoreflectance measurements of \ensuremath{\Lambda} in GaN, $^{71}\mathrm{GaN}$, and SiC between 150 and 850 K. The samples include bulk $c$- and $m$-plane wurtzite GaN grown by hydride vapor phase epitaxy (HVPE) and ammonothermal methods; homoepitaxial natural isotope abundant GaN and isotopically enriched $^{71}\mathrm{GaN}$ layers with thickness of 6--12 \ensuremath{\mu}m grown on $c$-, $m$-, and $a$-plane GaN substrates grown by HVPE; and bulk crystals of 4H and 6H SiC. In low dislocation density ($l{10}^{7}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$) bulk and homoepitaxial GaN, \ensuremath{\Lambda} is insensitive to crystal orientation and doping concentration (for doping $l{10}^{19}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$); $\mathrm{\ensuremath{\Lambda}}\ensuremath{\approx}200\phantom{\rule{0.16em}{0ex}}\mathrm{W}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ at 300 K and $\ensuremath{\approx}50\phantom{\rule{0.16em}{0ex}}\mathrm{W}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ at 850 K. In $^{71}\mathrm{GaN}$ epilayers at 300 K, \ensuremath{\Lambda} is $\ensuremath{\approx}15%$ higher than in GaN with natural isotope abundance. The measured temperature dependence of \ensuremath{\Lambda} in GaN is stronger than predicted by first-principles based solutions of the Boltzmann transport equation that include anharmonicity up to third order. This discrepancy between theory and experiment suggests possible significant contributions to the thermal resistivity from higher-order phonon scattering that involve interactions between more than three phonons. The measured \ensuremath{\Lambda} of 4H and 6H SiC is anisotropic, in good agreement with first-principles calculations, and larger than GaN by a factor of $\ensuremath{\approx}1.5$ in the temperature range $300lTl850\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. This paper provides benchmark knowledge about the thermal conductivity in wide-band-gap semiconductors of GaN, $^{71}\mathrm{GaN}$, and SiC over a wide temperature range for their applications in power electronics and optoelectronics.

Photoluminescence properties of N and B codoped fluorescent 4H-SiC and 6H-SiC single crystals

In this paper, N and B codoped 4H-SiC and 6H-SiC single crystals were prepared by physical vapour transport method and their photoluminescence properties were studied. The photoluminescence spectra, dopant concentrations, Raman spectra, and transmission spectra of these obtained crystals were characterized. It is observed that the fluorescent crystals radiate a warm white light that covers a wide band spectrum from 450 nm to 750 nm when they are excited by a 325 nm laser. The doped 4H-SiC single crystal presents a higher photoluminescence intensity and larger spectral band compared to that of doped 6H-SiC single crystal under the similar growth and measurement conditions. Further analyze by doping concentration and transmission spectra indicate that the photoluminescence property is strongly influenced by the N donor and B acceptor impurity level.

Femtosecond-laser-induced modifications on a 4H-SiC surface and their application to low-temperature diffusion at the Ni/SiC interface

We carried out cross-sectional transmission electron microscopy to investigate the diffusion at the Ni/SiC interface enhanced by femtosecond-laser-induced modifications. The surface of a 4H-SiC crystal was irradiated with femtosecond laser pulses along lines, and a Ni film was then deposited. A thin modified layer was introduced by densely irradiating the SiC surface with line spacing close to the laser-beam diameter. After annealing, a layered structure was formed at the Ni/SiC interface, composed of a C layer sandwiched between the layers of Ni and Ni–Si alloy. The formation of Ni-silicide, i.e., Ni2Si and NiSi, was detected by micro-Raman spectroscopy. The distribution of C visualized by electron energy loss spectroscopy clearly shows that C atoms were released from the dissolved SiC and subsequently diffused through the Ni-silicide layer towards the Ni film surface.

Structural characterization of the growth front of physical vapor transport grown 4H-SiC crystals using X-ray topography

The defect structure at the growth front of 4H-SiC single crystal boules grown by the physical vapor transport (PVT) growth method has been investigated using X-ray topography. Plan-view observations of the growth front of the boules revealed that basal plane dislocations (BPDs) were often nucleated at the outcrops of threading screw dislocations during growth. The observations also revealed that BPDs introduced in the facet and near-facet regions were hardly multiplied during the PVT growth process, and thus the crystal portions just beneath these regions contained very low densities of BPDs. The cross-sectional observations of the grown boules confirmed this result and further revealed that a number of BPDs were introduced in the crystal portions well distant from the growth front. They are thought to be introduced via dislocation multiplication due to large thermoelastic stresses imposed on the shoulder parts of the grown boules during PVT growth.

An Interpretation for Defect-Induced Structural Transformation in SiC

Silicon carbide (SiC) has been considered as one of the alternative power semiconductor materials due to its excellent properties such as wide band gap, high break down field, and high thermal conductivity. Although SiC with 3C (zinc blende) is suitable for high-frequency power devices from its high electron mobility and high electron-saturation-velocity, SiC is well known as having dozens of polytypes including 4H and 6H in addition to 2H (wurtzite) and 3C that consist of different ordered stacking sequences of SiC atomic double layers. The 3C-SiC is believed to be more stable than the hexagonal structure at low temperatures. In contrast, 2H-SiC, which has the simplest stacking sequence, is rarely observed at high temperatures. Moreover, point defects also affect the stable polytype in SiC. Heavily Nitrogen (N)-doped single crystals of 6H-SiC were completely transformed into 3C-SiC by annealing in vacuum at presence of Si vapor at 2080 K and 2180 K (hereafter Case I). The 3C-SiC-like bands was also observed in 4H-SiC epilayers with heavily N-doping after thermal annealing (hereafter Case II). Presuming that vacancy formation is related to temperature, point defects such as vacancy and N in SiC are crucial factor for the structural transformation between hexagonal and cubic structures. In this study, the structural transformation in SiC is simply interpreted by considering point defect formation with the aid of ab initio calculations. Ab initio total energy calculations in a √3×√3×12 unit cell imply that stable stacking for SiC is 6H with Si-vacancy (VSi), 4H with C-vacancy (VC) and N substituting for Si (NSi), and 3C with N substituting for C (NC), whereas 2H-stacking does not appear as a stable stacking in these systems. Furthermore, the formation energy calculations reveal that vacancy formation depends on C chemical potential m C, where VSi and VC formations are favorable at large m C (corresponding to C-rich) and small m C (Si-rich), respectively. On the other hand, NC formation is more favorable than NSi formation over the entire range of m C and independent of conditions because of very small difference in covalent radius between N and C. Comparing these calculated results with the experimental finding in the Case I for transformation from 6H to 3C, thermal treatment with presence of Si vapor at high temperatures suppresses VSi formation favoring 6H-stacking while it enhances VC formation to be occupied by N (NC) in addition to N substitution for C (NC) that transform 6H to 3C. The Case II can be also interpreted by considering NC. Thermal annealing for N-doped 4H-SiC favored by VC easily produces NC with N occupying VC and substituting for C to realize 3C-SiC bands at high N-doped region in 4H-SiC epilayers. These results suggest that NC is crucial for the transformation from hexagonal stacking such as 6H and 4H to cubic stacking 3C. In order to give physical interpretation for the transformation to 3C-SiC with NC, the interaction energies Jn between nth neighbor SiC double layers are estimated in the range of n ≤ 3 using the axial next nearest neighbor Ising (ANNNI) model and calculated total energies for SiC polytypes obtained in this study. The calculated results elucidate that the absolute value of positive J 1 (51.70 meV) with J 3 (9.92 meV) favoring 3C-stacking is much larger than that of negative J 2 (-16.66 meV) inducing hexagonal stacking. It should be noted that the Jn values are one order of magnitude greater than those of perfect SiC such as J 1 (2.33 meV), J 2 (-1.41 meV), and J 3 (0.51 meV). This implies that the layer interaction in SiC becomes strong and long-range due to N-doping. Considering coordinate of (|J 2|/J 1, J 3/J 1) in the ANNNI phase diagram, it is also found that (0.31, 0.19) for SiC with NC is located in the stable region of 3C and is more distant from the multi-phase degeneracy point (0.5, 0) inducing polytype and phase boundary between 3C and 4H than (0.61, 0.21) for perfect SiC. This clarifies that the large J 1 in SiC with NC stabilizes 3C-stacking to dominate the structural transformation to 3C due to N-doping. Furthermore, atomistic interaction between the nearest neighbor layers corresponding to J 1 is also qualitatively discussed in terms of electrostatic interaction between bond charges located at the center of interatomic bonds and that between ionic charges located at the lattice sites on the basis of a simple energy description and charge distribution obtained by ab initio calculations.

Evaluation of Model for Determining Nitrogen Doping Concentration from Resultant Strain in Heavily Doped 4H-SiC Crystals

Significant strain in 4H-SiC substrates can be introduced by impurity incorporation in heavily doped 4H-SiC crystals. The non-destructive X-ray double-crystal contour mapping method we reported recently is a powerful tool to estimate the lattice strain levels in 4H-SiC substrates with different doping concentrations. The lattice strain maps were derived from 11-20, 1-100 and 0008 reflections. Result shows that lattice strains within the basal plane and along the [0001] direction are in the order of 10-3 and 10-4 respectively. Hall effect measurements performed to determine the doping concentration of 4H-SiC substrates show an increase in doping concentration with the decrease of contact resistivity. X-ray rocking curve measurements were employed to confirm the existence of significant lattice distortion in heavily doped 4H-SiC substrates, which is in good agreement with the lattice strain analysis based on X-ray contour mapping method.

In-Situ Synchrotron X-Ray Topography Study on the Stress Relaxation Process in 4H-SiC Homoepitaxial Layers

Recent advances made towards the improvement of the quality of 4H silicon carbide (4H-SiC) have enabled many successful applications in the power device industry. While defect densities in homoepitaxial active layers have been lowered significantly, there is still a strong interest in understanding the formation mechanism of crystal defects such as dislocations preferably through direct observation. During 4H-SiC homoepitaxy and post-growth annealing, the process of stress relaxation has previously been reported to lead to the formation of misfit dislocations or interfacial dislocations (IDs). [1] The driving force for such a relaxation process is believed to be the lattice misfit induced by the difference in nitrogen doping concentrations across the substrate/epilayer interface. According to van der Merwe [2], at initial stage of epitaxy growth, misfit is accommodated by elastic strain in epilayers; as the growth continues, misfit strain builds up until a critical amount when crystals start to deform plastically with misfit dislocations introduced at the substrate/epilayer interface, relaxing additional elastic strain and minimizing the free energy of the epi-substrate system. Matthews and Blakeslee, [3] from a mechanics point of view, predict the onset of stress relaxation process to be the moment when the mismatch stress applied on a single threading glide dislocation in the epilayer (basal plane dislocation in the case of 4H-SiC homoepitaxy) exceeds the sum of the line tension and the Peierls-Nabarro stress as the epilayer grows thicker. Nevertheless, the direct observation of the stress relaxation process in silicon carbide crystals has not yet been reported. In this paper, we present an in-situ study in which a sample cut from a 150mm commercial n-/n+ 4H-SiC homoepitaxial wafer was subject to high-temperature heat treatment while sequential synchrotron white beam X-ray topographs were recorded simultaneously. The heat treatment was carried out in a halogen lamp furnace and the local temperature was elevated to as high as 1600°C. Figure 1 shows a series of topographs recorded in this manner and the time interval between consecutive topographs is 10 seconds. As time advances, a basal plane dislocation (BPD) in the epitaxial layer is observed to glide from left to right, depositing a straight segment of misfit dislocation right at the substrate/epilayer interface. Figure 2 schematically shows the entire process. Such dynamic observations of relaxation process suggest that the lattice misfit once again exceeds the critical value during high temperature heat treatment. Since the epilayer thickness does not change, it can be inferred that the misfit strain simply increases as temperature is raised. The reason may be that the thermal expansion coefficient of 4H-SiC crystal is a function of doping concentration. Sasaki et. al [4] also confirmed this by measuring the lattice constants of both n+ substrate and n- epilayer at elevated temperatures. [1] M. Dudley, H. Wang, J. Guo, Y. Yang, B. Raghothamachar, J. Zhang, B. Thomas, G.Y. Chung, E. Sanchez, D.M. Hansen, S.G. Mueller, MRS Advances, 1(2), 91-102 (2016). [2] J.H. van der Merwe, J. Appl. Phys. 34, 117 (1963). [3] J.W. Matthews, and A.E. Blakeslee, Journal of Crystal Growth, 27, 118–125 (1974). [4] S. Sasaki, J. Suda, and T. Kimoto, Materials Science Forum, 717-720, 481-484 (2012) Figure 1

Evaluation of Model for Determining Nitrogen Doping Concentration from Resultant Strain in Heavily Doped 4H-SiC Crystals

Lattice strain in 4H-SiC substrate wafers can strongly affect the performance of power electronic devices especially under the high temperature operation. The impurity incorporation in highly doped 4H-SiC crystals can result in significant lattice parameter change. Recently we reported [1] the synchrotron X-ray topographic contour mapping [2] technique to deconvolute lattice parameter variations from lattice tilt and thus generate strain maps. These strain maps have been incorporated into an anisotropic elasticity model to derive the nitrogen doping concentration variation in the 4H-SiC wafer. Doping distribution can be derived using a set of anisotropic strain maps detected by recording series of diffraction contours across the same region. The nondestructive contour mapping method we developed is capable of not only determining the concentration but also the distribution of the doping i.e. a doping map. In order to verify the doping level determined by contour mapping, we prepared samples with different N-doping levels. Contacts were created by depositing Ni using e-beam evaporator followed by rapid annealing. Hall effect measurements have been carried out on these samples to measure the carrier concentration in order to determine the doping values. The measured values are found to be in good agreement with the doping map derived using our contour mapping method. Reference Yu Yang, Jianqiu Guo, Balaji Raghothamachar, Xiaojun Chan, Taejin Kim, Michael Dudley, J. Electron. Mater. 47(2), 938-943 (2018).J. Guo, Y. Yang, B. Raghothamachar, M. Dudley, and S. Stoupin, J. Electron. Mater. 47(2), 903-909 (2018).