Nanopipes in GaN: photo-etching and TEM study

Lazar, Sorin; Weyher, J.L.; Macht, L.; Tichelaar, F.D.; Zandbergen, H.W.

doi:10.1051/epjap:2004047

Cited by 14 publications

(7 citation statements)

References 23 publications

(32 reference statements)

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“…However, etching experiments with HCl show the formation of hexagonal etch pits in the GaN layer indicating the presence of screw dislocations in [0001] direction (not shown here). Thus, the formation mechanism of these voids could be identical to the one observed in c-oriented GaN, namely open-core screw-dislocations [4]. In the [1-100] direction ( Fig.…”

supporting

confidence: 53%

Defect structure of a‐plane GaN grown by hydride and metal‐organic vapor phase epitaxy on r‐plane sapphire

Kröger

Paskova

Ḿonemar

et al. 2007

Phys. Status Solidi (c)

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To obtain a deeper insight into the mechanism of defect formation in a-plane GaN the defect nature in such films grown by metal-organic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE) was investigated by means of transmission electron microscopy. The films showed, beside the frequently found basal plane stacking faults and threading dislocations, prismatic stacking faults originating at the film/substrate interface and facetted voids. The density of basal plane stacking fault was about 10 5 cm -1 and the density of partial dislocations was in the range of 10 10 cm -2, accordingly. Using selected area diffraction the epitaxial relationship between film and layer was determined. Based on these findings the impact of lattice mismatch on the observed defect characteristic is discussed.

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supporting

confidence: 53%

Defect structure of a‐plane GaN grown by hydride and metal‐organic vapor phase epitaxy on r‐plane sapphire

Kröger

Paskova

Ḿonemar

et al. 2007

Phys. Status Solidi (c)

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“…The origin of such rough morphology is not understood at present). In (whiskers, hillocks) on all types of dislocations, nano-pipes and inversion domain boundaries [21][22][23][24]. Since the mechanism of photo-etching of SiC in KOH solutions is similar to that of GaN (electroless etching with the crucial role of holes for surface reactions, see [25]), the ineffectiveness' in revealing of all dislocations in SiC could, therefore, indicate that not all dislocations result in recombination of photogenerated carriers.…”

Section: Pec Etchingmentioning

confidence: 99%

Defect‐selective etching of SiC

Weyher

Lazar

Borysiuk

et al. 2005

Physica Status Solidi (a)

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PACS 61.72.Ff, 82.50.Hp Two methods of defect-selective etching of SiC are described: (i) orthodox etching in molten KOH -NaOH eutectic with 10% of MgO powder (E + M etch) and (ii) electroless photo-etching in aqueous KOH solutions (PEC method). The first etch shows similar effectiveness in revealing different type of dislocations, micropipes and stacking faults, as the commonly used molten KOH. The second approach is new for studying defects in SiC and is most suitable for revealing stacking faults both on the disoriented (0001) basal planes and on the (1 100) cleavage surfaces. Cross-calibration of both techniques and examples of calibration of PEC etch features by TEM are shown.

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“…: direct calibration by X-ray topography [1] (suitable for dislocation density below 10 5 cm -2 ), comparison with cathodoluminescence (CL) [2], electron beam induced current (EBIC) [3] or another calibrated etching method [4], sequent etching [5] and calibration by TEM, as in e.g. [4][5][6][7][8]. 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.…”

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%

Orthodox etching of HVPE-grown GaN

Weyher

Lazar

Macht

et al. 2007

Journal of Crystal Growth

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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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Nanopipes in GaN: photo-etching and TEM study

Cited by 14 publications

References 23 publications

Defect structure of a‐plane GaN grown by hydride and metal‐organic vapor phase epitaxy on r‐plane sapphire

Defect structure of a‐plane GaN grown by hydride and metal‐organic vapor phase epitaxy on r‐plane sapphire

Defect‐selective etching of SiC

Orthodox etching of HVPE-grown GaN

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