Polarity determination of rough and smooth surface grains in AlN crystals

Nyakiti, Luke O.; Lee, R. G.; Gu, Zheng; Edgar, James H.; Chaudhuri, J.

doi:10.1002/crat.201200005

Cited by 2 publications

(2 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…18−20 Control of polarity is also essential for device design due to the strong polarization-induced internal electric fields. 21 The experimental results of Filip et al 19 in a tungsten setup using Al-polar, Npolar, and mixed-polar seeds showed that the colorless or light brown Al-polar crystals have better light transmission than the dark brown N-polar crystals. In general, the growth of N-polar crystals is more likely to introduce carbon/oxygen impurities and point defects, which result in low UV transmission, although N-polar growth can usually maintain a stable and uniform step-flow growth mechanism.…”

Section: Introductionmentioning

confidence: 98%

“…It is reported that the growth setup, growth process, and seed polarities have a significant effect on the UV transparency of AlN crystals. In particular, crystal polarity is a key factor in controlling the AlN surface morphology and growth mechanism, since it strongly impacts the incorporation of unintentionally doped impurities (O, C, and Si) in AlN crystals and their interplay with intrinsic point defects and, hence, the electrical and optical properties of AlN. − Control of polarity is also essential for device design due to the strong polarization-induced internal electric fields . The experimental results of Filip et al in a tungsten setup using Al-polar, N-polar, and mixed-polar seeds showed that the colorless or light brown Al-polar crystals have better light transmission than the dark brown N-polar crystals.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Toward Φ56 mm Al-Polar AlN Single Crystals Grown by the Homoepitaxial PVT Method

Lei²,

et al. 2022

Crystal Growth & Design

View full text Add to dashboard Cite

Crack-free and parasitic-free Al-polar aluminum nitride (AlN) single crystals up to Φ56 mm were iteratively grown by the homoepitaxial physical vapor transport method. The detailed iterative growth processes from the spontaneous AlN boules to Φ56 mm single crystals were presented. Our growth experiments revealed that stable growth of large Al-polar crystals with good structural quality and UV transparency was possible using a pure tungsten setup. For each iteration, the initial expansion angle, which was dominated by the radial temperature gradient (ΔT r ), reached 50−60°under our specific growth system and growth conditions and then gradually decreased to 10−20°during the growth process. For all as-grown crystals, mirror-like facets with a step-flow growth mode could be observed. However, the {101̅ 0} side planes were strongly suppressed when using larger AlN seeds. Material characterization showed that the full width at half maximum of symmetric and asymmetric highresolution X-ray diffraction rocking curves was 84−144 arcsec and 45−70 arcsec, respectively. The average etch pit density evaluated by preferential chemical etching was approximately 8.5 × 10 4 cm −2 . The optical transmission spectra revealed that the entire wafer exhibited excellent ultraviolet (UV) transparency, with absorption coefficients of 19−29 cm −1 in the UV range of 4.43−4.77 eV (260−280 nm).

show abstract

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Toward Φ56 mm Al-Polar AlN Single Crystals Grown by the Homoepitaxial PVT Method

Lei²,

et al. 2022

Crystal Growth & Design

View full text Add to dashboard Cite

show abstract

Thermodynamics of inversion-domain boundaries in aluminum nitride: Interplay between interface energy and electric dipole potential energy

Zhang

Xie

Guo

et al. 2018

Journal of Applied Physics

View full text Add to dashboard Cite

Aluminum nitride (AlN) has a polar crystal structure that is susceptible to electric dipolar interactions. The inversion domains in AlN, similar to those in GaN and other wurtzite-structure materials, decrease the energy associated with the electric dipolar interactions at the expense of inversion-domain boundaries, whose interface energy has not been quantified. We study the atomic structures of six different inversion-domain boundaries in AlN, and compare their interface energies from density functional theory calculations. The low-energy interfaces have atomic structures with similar bonding geometry as those in the bulk phase, while the high-energy interfaces contain N-N wrong bonds. We calculate the formation energy of an inversion domain using the interface energy and dipoles' electric-field energy, and find that the distribution of the inversion domains is an important parameter for the microstructures of AlN films. Using this thermodynamic model, it is possible to control the polarity and microstructure of AlN films by tuning the distribution of an inversion-domain nucleus and by selecting the low-energy synthesis methods.

show abstract

Polarity determination of rough and smooth surface grains in AlN crystals

Cited by 2 publications

References 19 publications

Toward Φ56 mm Al-Polar AlN Single Crystals Grown by the Homoepitaxial PVT Method

Toward Φ56 mm Al-Polar AlN Single Crystals Grown by the Homoepitaxial PVT Method

Thermodynamics of inversion-domain boundaries in aluminum nitride: Interplay between interface energy and electric dipole potential energy

Contact Info

Product

Resources

About