Recent advances in defect-selective etching of GaN

Weyher, J.L.; Brown, Paul D.; Rouvière, Jean-Luc; Wosiński, T.; Zauner, A.; Grzegory, I.

doi:10.1016/s0022-0248(99)00669-7

Cited by 130 publications

(112 citation statements)

References 16 publications

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“…Among these methods the latter is the most attractive because it offers the possibility of establishing not only the one-to-one correspondence between the etch features and the individual defects but also to establish a correlation between different features and their causative defects. As a result TEM, has been the main technique used for calibration of recently developed defect-selective etching methods for GaN [9][10][11]. Two approaches are usually employed for this purpose, namely (i) comparison of dislocation density established by TEM with the density of etch pits (etch features), e.g.…”

Section: Introductionmentioning

confidence: 99%

“…TEM was most frequently used for calibration of different etching methods recently developed for revealing dislocations in GaN [4,[6][7][8][9][10][11][12]. As a rule orthodox etching in molten salts (KOH [9], eutectic alloy of KOH-NaOH=E etch [11] and E+MgO=E+M etch [13]) and hot acids [11,14] results in formation of pits of different sizes.…”

Section: Introductionmentioning

confidence: 99%

“…As a rule orthodox etching in molten salts (KOH [9], eutectic alloy of KOH-NaOH=E etch [11] and E+MgO=E+M etch [13]) and hot acids [11,14] results in formation of pits of different sizes. The attempts to attribute the size of pits to the type of dislocations showed unambiguously that the largest pits are formed on nano-pipes, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Orthodox etching of HVPE-grown GaN

Weyher

Lazar

Macht

et al. 2007

Journal of Crystal Growth

116

103

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Orthodox etching of HVPE-grown GaN in molten eutectic of KOH + NaOH (E etch) and in hot sulfuric and phosphoric acids (HH etch) is discussed in detail. Three size grades of pits are formed by the preferential E etching at the outcrops of threading dislocations on the Ga-polar surface of GaN. Using transmission electron microscopy (TEM) as the calibration tool it is shown that the largest pits are formed on screw, intermediate on mixed and the smallest on edge dislocations. This sequence of size does not follow the sequence of the Burgers values (and thus the magnitude of the elastic energy) of corresponding dislocations. This discrepancy is explained taking into account the effect of decoration of dislocations, the degree of which is expected to be different depending on the lattice deformation around the dislocations, i.e. on the edge component of the Burgers vector. It is argued that the large scatter of optimal etching temperatures required for revealing all three types of dislocations in HVPE-grown samples from different sources also depends upon the energetic status of dislocations. The role of kinetics for reliability of etching in both etches is discussed and the way of optimization of the etching parameters is shown.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Orthodox etching of HVPE-grown GaN

Weyher

Lazar

Macht

et al. 2007

Journal of Crystal Growth

116

103

View full text Add to dashboard Cite

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“…For gallium nitride, Weyher et al [18][19][20] established the association between three etch pit sizes and specific types of dislocations; the largest pits formed on nano-pipes, the medium size pits formed on screw and mixed dislocations, and the smallest pits on edge type dislocations. A similar relationship was reported for HCl etching of GaN at 600 o C [21].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2007

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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.

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“…6,7 This leads to photoluminescence spectra with very well-resolved excitonic transition lines of widths below 1 meV. 8 Recently, Mg-doped high-pressure-grown bulk GaN crystals were shown to be semi-insulating with perfect crystallographic structure. The dislocation density in these crystals was determined by selective defect etching and was found to be of the order of 10 2 per cm 2 , which is more than 6-7 orders of magnitude less than in heteroepitaxially grown GaN.…”

Section: ϫ2mentioning

confidence: 99%

GaN–AlGaN heterostructure field-effect transistors over bulk GaN substrates

Khan

Yang

Knap

et al. 2000

Applied Physics Letters

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We report on AlGaN/GaN heterostructures and heterostructure field-effect transistors (HFETs) fabricated on high-pressure-grown bulk GaN substrates. The 2d electron gas channel exhibits excellent electronic properties with room-temperature electron Hall mobility as high as μ=1650 cm2/V s combined with a very large electron sheet density ns≈1.4×1013 cm−2. The HFET devices demonstrated better linearity of transconductance and low gate leakage, especially at elevated temperatures. We also present the comparative study of high-current AlGaN/GaN HFETs (nsμ>2×1016 V−1 s−1) grown on bulk GaN, sapphire, and SiC substrates under the same conditions. We demonstrate that in the high-power regime, the self-heating effects, and not a dislocation density, is the dominant factor determining the device behavior.

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Recent advances in defect-selective etching of GaN

Cited by 130 publications

References 16 publications

Orthodox etching of HVPE-grown GaN

Orthodox etching of HVPE-grown GaN

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

GaN–AlGaN heterostructure field-effect transistors over bulk GaN substrates

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