Wet KOH etching of freestanding AlN single crystals

Bickermann, Matthias; Schmidt, Stephan; Epelbaum, Boris M.; Heimann, Paul; Nagata, S.; Winnacker, A.

doi:10.1016/j.jcrysgro.2006.12.037

Cited by 49 publications

(36 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dislocations penetrating this surface form hexagonal pits after 120 s of etching at 350°C, i.e., parameters also used for nominally pure AlN [42,43] . Results are shown in Fig.…”

Section: Structural Properties and Raman Spectramentioning

confidence: 99%

Growth of AlN bulk crystals on SiC seeds: Chemical analysis and crystal properties

Bickermann

Filip²,

Epelbaum³

et al. 2012

Journal of Crystal Growth

View full text Add to dashboard Cite

Highlights:-Different growth conditions used to control SiC incorporation in AlN bulk growth -Phonon energies and band-gap of the crystals close to 'pure AlN' -Deep-UV opacity regardless of silicon and carbon content -Two types of samples with very different absorption and luminescence -No pseudo-binary alloy, but highly compensated, Si/C co-doped AlN Abstract AlN single crystals are grown by physical vapor transport (PVT) in sintered TaC crucibles in the presence of SiC, i.e. by seeding on 6H-SiC or by adding SiC to the AlN source material. Different growth conditions, i.e. growth temperatures T = 1900-2050°C and off-orientation angles in respect to [0001]  = 0-42°, are applied in order to investigate to which extent the incorporation of Si and/or C can be controlled during PVT growth. Chemical analysis is performed by energy-dispersive X-ray analysis (EDX), secondary ion mass spectrometry (SIMS), and Rutherford backscattering spectroscopy (RBS). The grown crystals are significantly contaminated with Si and C in the range of several atomic percents, but they do not represent pseudo-binary AlN-SiC solid solutions. Samples cut from these crystals are probed by Raman micro-spectroscopy, optical absorption, cathodoluminescence (CL), and near band-gap photoluminescence (PL) in order to evaluate the crystal properties. All crystals exhibit phonon bands at the positions of AlN phonon energies, and a low-temperature band-gap exceeding 5.8 eV, which is only slightly lower than the band-gap of pure AlN. On the other hand, the samples show very different optical properties below the band-gap, including coloration. As the changes in optical properties do not correlate to chemical analysis, we suggest that self-compensation of silicon 2 and carbon as well as formation of intrinsic defects lead to a complex compensation scenario in the samples. The grown crystals are thus to be considered as highly compensated, Si/C co-doped AlN.

show abstract

“…Dislocations penetrating this surface form hexagonal pits after 120 s of etching at 350°C, i.e., parameters also used for nominally pure AlN [42,43] . Results are shown in Fig.…”

Section: Structural Properties and Raman Spectramentioning

confidence: 99%

Growth of AlN bulk crystals on SiC seeds: Chemical analysis and crystal properties

Bickermann

Filip²,

Epelbaum³

et al. 2012

Journal of Crystal Growth

View full text Add to dashboard Cite

show abstract

“…; the set-up and etching process are discussed in detail in Ref. [5]. After final cleaning, the etched surfaces were investigated by optical microscopy and scanning electron microscopy (SEM).…”

Section: Contributed Articlementioning

confidence: 99%

“…Wet chemical etching is a reasonable, reliable and simple method to analyze the abundance and density of dislocations and other defects in III-nitrides [1][2][3]. Recently we investigated wet chemical etching of as-grown facets of freestanding high-quality, yet mm-sized AlN single crystals [4,5]. In this paper, we report first results of wet chemical etching, dislocation content, and mosaicity analysis of 1-inch diameter AlN bulk single crystals obtained by seeded growth.…”

mentioning

confidence: 99%

Structural properties of aluminum nitride bulk single crystals grown by PVT

Bickermann

Epelbaum

Filip

et al. 2008

Phys. Status Solidi (c)

Self Cite

View full text Add to dashboard Cite

Defect analysis is performed on 1‐inch diameter bulk AlN crystals grown on AlN‐on‐SiC templates by physical vapour transport. The mean density of threading dislocations as evaluated by wet chemical etching is about 4 × 104 cm–2; mosaicity of the crystals is mostly inherited from the quality of the SiC and the AlN‐on‐SiC template used as seed. Comparing crystals grown without and with growth optimization, the dislocation topography is significantly different, and in crystals grown under optimized conditions, low angle grain boundaries have a more pronounced tendency to dissolve into dislocation bunches and thus a lower density at the crystal top. This corresponds to a ‘coarser’. mosaic structure as observed in X‐ray rocking curve measurements. In summary, AlN bulk crystals grown on AlN‐on‐SiC templates under optimized conditions show not only significant improvement in cracking mitigation and optical homogeneity, but also in structural quality, within a single growth run. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

“…Since AlN is an anisotropic material, Al-or N-polar faces etch at different rates. Bickermann et al [12][13][14][15] performed wet KOH etching on a free standing AlN crystal. They reported a lack of defect etching features on as grown rhombohedral and prismatic facets as N-polar basal planes exhibited hexagonal pyramid hillocks for etching at 240 o C and Alpolar basal planes produced hexagonal etch pits of uniform size.…”

Section: Introductionmentioning

confidence: 99%

DEFECT SELECTIVE ETCHING OF THICK AlN LAYERS GROWN ON 6H-SIC SEEDS – A TRANSMISSION ELECTRON MICROSCOPY STUDY

et al. 2007

View full text Add to dashboard Cite

In the present study, the type and densities of defects in AlN crystals grown on 6H-SiC seeds by the sublimation-recombination method were assessed. The positions of the defects in AlN were first identified by defect selective etching (DSE) in molten NaOH-KOH at 400 °C for 2 minutes. Etching produced pits of three different sizes: 1.8, 2.4, and 2.9 µ m. The etch pits were either aligned together forming a sub-grain boundary or randomly distributed. The smaller etch pits were either isolated or associated with larger etch pits. After preparing cross-sections of the pits by the focused ion beam (FIB) technique, transmission electron microscopy (TEM) was performed to determine the dislocation type (edge, mixed or screw) associated with a specific etch pit size. Preliminary TEM bright field and dark field imaging using different zone axes and diffraction vectors indicates an edge dislocation with a Burgers vector 1/3 ] 0 2 11 [ is associated with the smallest etch pit size.

show abstract

Wet KOH etching of freestanding AlN single crystals

Cited by 49 publications

References 27 publications

Growth of AlN bulk crystals on SiC seeds: Chemical analysis and crystal properties

Growth of AlN bulk crystals on SiC seeds: Chemical analysis and crystal properties

Structural properties of aluminum nitride bulk single crystals grown by PVT

DEFECT SELECTIVE ETCHING OF THICK AlN LAYERS GROWN ON 6H-SIC SEEDS – A TRANSMISSION ELECTRON MICROSCOPY STUDY

Contact Info

Product

Resources

About