Strain mapping of GaN substrates and epitaxial layers used for power electronic devices by synchrotron X-ray rocking curve topography

Liu, Yafei; Chen, Zeyu; Hu, Shanshan; Peng, Hongyu; Cheng, Qianyu; Dudley, Michael

doi:10.1016/j.jcrysgro.2022.126559

Cited by 5 publications

(4 citation statements)

References 23 publications

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“…In a survey of five areas on a wafer, they found an average of 96.3% of dislocations to be mixed-type while 3% were pure edge-type and the remaining 0.8% were screw dislocations in a wafer with a low overall concentration of defects (5 × 10 3 /cm 2 ). A second recent paper explores strain mapping using X-ray rocking curve topography in a synchrotron beam [45]. While the efforts here demonstrate the comprehensive characterization power of the synchrotron XRT method, the method itself is very challenging to introduce in any type of regular quality control feedback for crystal growers.…”

Section: Structural Defectsmentioning

confidence: 98%

Progress in Ammonothermal Crystal Growth of Gallium Nitride from 2017–2023: Process, Defects and Devices

Stoddard

Pimputkar

2023

Crystals

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Gallium nitride continues to be a material of intense interest for the ongoing advancement of electronic and optoelectronic devices. While the bulk of today’s markets for low-performance devices is still met with silicon and blue/UV LEDs derived from metal–organic chemical vapor deposition gallium nitride grown on foreign substrates such as sapphire and silicon carbide, the best performance values consistently come from devices built on bulk-grown gallium nitride from native seeds. The most prominent and promising of the bulk growth methods is the ammonothermal method of high-pressure solution growth. The state-of-the-art from the last five years in ammonothermal gallium nitride technology is herein reviewed within the general categories of growth technology, characterization and defects as well as device performance.

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Section: Structural Defectsmentioning

confidence: 98%

Progress in Ammonothermal Crystal Growth of Gallium Nitride from 2017–2023: Process, Defects and Devices

Stoddard

Pimputkar

2023

Crystals

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“…This method has the advantage that Burgers vector characterization of dislocations can be carried out using a single reflection from a commercial (000) substrate wafer without the need for additional reflections (as required for 𝐠 • 𝐛 = & 𝐠 • 𝐛 × 𝐥 = criteria) or axial-cut wafers to characterize dislocations parallel to the c-axis. More details on ray tracing simulations of dislocations in GaN can be found elsewhere [11]. Table I summarizes the results of simulations for different types of dislocations expected to be observed in GaN substrates.…”

Section: Ray Tracing Simulations Of Dislocationsmentioning

confidence: 99%

“…Analysis of dislocations indicates that no BPDs are observed and TEDs, TSDs and TMDs can be identified by comparing the image contrasts with ray tracing simulation images (Table I). TMDs dominate among the threading dislocations accounting for more than 90% of observed areas [11]. The absence of BPDs is expected since the low temperatures (< 600℃) and relatively small temperature gradients at which ammonothermal growth is carried out is unlikely to generate sufficiently large thermal gradient stresses to induce deformation.…”

Section: Gan Substratesmentioning

confidence: 99%

(Invited) Application of Synchrotron X-Ray Topography Techniques to the Analysis of Defect Microstructures in Bulk GaN Substrates and Epilayers for Power Devices

Liu¹,

Hu²,

Chen³

et al. 2023

ECS Trans.

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The study of defects and strain in GaN substrates and epilayers for vertical device development using synchrotron X-ray topography techniques is presented. Synchrotron monochromatic beam X-ray topography (SMBXT) studies show that ammonothermal-grown GaN substrate wafers have the lowest dislocation densities while patterned hydride vapor phase epitaxy (HVPE) GaN reveal a starkly heterogeneous distribution of dislocations with large areas containing low threading dislocation densities and HVPE GaN substrates contain high dislocation densities. Epitaxial growth does not nucleate new defects but interactions of dislocations with point defects can cause changes in dislocation configurations. Rocking curve Analysis by Dynamical Simulation (RADS) is shown to be effective in analysis of implantation by correlating the depth profile of strain with the doping profile. Removal of lattice damage induced by implantation requires annealing with proper capping or under high pressures to limit loss of material and lattice distortion. Inductively coupled plasma (ICP) etching may introduce strain in GaN material that can be partially recovered by TBCl etching. Diffusion doping does not introduce new strains in GaN material while neutron transmutation doping at low levels can lead to curing of defects while higher levels lead to irradiation damage and nucleation of new defects.

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“…This configuration is similar to that designed by Petroff et al (1980) for synchrotron radiation plane-wave topography (SXPWT) and employed in experiments reported by others (Sauvage, 1980;Klapper, 1996). This is also referred to as rocking curve topography (RCT) in a number of recent studies (Macrander et al, 2019;Liu et al, 2022), which is different from rocking curve imaging (Lubbert et al, 2000;Yang et al, 2010). In this work, the term SXPWT is adopted to describe this technique as the beam incident on the sample is almost parallel.…”

Section: Introductionmentioning

confidence: 99%

Quantitative analysis of dislocations in 4H-SiC wafers using synchrotron X-ray topography with ultra-high angular resolution

Peng¹,

Chen²,

Liu³

et al. 2022

J Appl Crystallogr

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Utilization of an Si(331) beam conditioner together with an Si(111) double-crystal monochromator (DCM) enables the angular resolution of synchrotron X-ray topography to be increased by an order of magnitude compared with grazing-incidence topography or back-reflection topography conducted with the DCM alone. This improved technique with extremely small beam divergence is referred to as synchrotron X-ray plane-wave topography (SXPWT). This study demonstrates that the rocking curve width of 4H-SiC 0008 in PWT is only 2.5′′ and thus the lattice distortion at the scale of 1′′ will significantly affect the diffracted intensity. This work reports the ultra-high angular resolution in SXPWT which enables detailed probing of the lattice distortion outside the dislocation core in 4H-SiC, where the sign of the Burgers vector can be readily determined through comparison with ray-tracing simulations.

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Strain mapping of GaN substrates and epitaxial layers used for power electronic devices by synchrotron X-ray rocking curve topography

Cited by 5 publications

References 23 publications

Progress in Ammonothermal Crystal Growth of Gallium Nitride from 2017–2023: Process, Defects and Devices

Progress in Ammonothermal Crystal Growth of Gallium Nitride from 2017–2023: Process, Defects and Devices

(Invited) Application of Synchrotron X-Ray Topography Techniques to the Analysis of Defect Microstructures in Bulk GaN Substrates and Epilayers for Power Devices

Quantitative analysis of dislocations in 4H-SiC wafers using synchrotron X-ray topography with ultra-high angular resolution

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