Dislocation generation in GaN heteroepitaxy

Wu, Xiang; Fini, P.; Tarsa, E. J.; Heying, B.; Keller, S.; Mishra, Umesh K.; DenBaars, Steven P.; Speck, James S.

doi:10.1016/s0022-0248(98)00240-1

Cited by 276 publications

(204 citation statements)

References 20 publications

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“…Also seen are arrays of depressions which most probably consist of edge TDs (Fig. 1d), in agreement with TEM studies reporting TDs with predominantly mixed character with b = 1/3 1123 , pure edge character with b = 1/3 1120 , and very few of pure screw character with b = 0001 in as-grown device quality MOCVD GaN [8][9][10][11]. It is important to note that although grown on substrate surfaces of increasing roughness, the images in Figures 1c and 1d are very similar, both indicative of high-quality, fully coalesced GaN sur- faces that are not different from surfaces observed on GaN grown on undamaged sapphire [12].…”

supporting

confidence: 89%

“…The contrast of the truncated features seen on top of the substrate surface under these diffraction conditions appears to be due to either stacking faults or threading dislocations along the {1101} GaN planes. We speculate that these features are associated with the HT islands which are formed during the early stages of MOCVD GaN growth [8]. In order to accommodate the inclined sapphire substrate surface and yet grow in a nearly perfect {0001} GaN {0001} sapphire orientation relationship, these HT islands apparently adapt an asymmetrical shape, with longer facets towards the lower (left) side and shorter facets towards the upper (right) side of the substrate surface.…”

mentioning

confidence: 95%

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High-quality GaN on intentionally roughened c-sapphire

et al. 2003

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supporting

confidence: 89%

mentioning

confidence: 95%

High-quality GaN on intentionally roughened c-sapphire

et al. 2003

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“…Instead of the ABAB stacking sequence, characteristic of hexagonal GaN, we can find the typical cubic phase ABCABC stacking sequence of atomic planes. Many groups reported the existence of cubic inclusions which has its origin in the low temperature nucleation layer or near the interface between the nucleation layer and the epitaxial layer [12][13][14].…”

Section: Observationsmentioning

confidence: 99%

Defect formation in GaN grown on vicinal 4H‐SiC (0001) substrates

Rudziński¹,

Jezierska

Weyher

et al. 2007

Physica Status Solidi (a)

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We report a comparative study of wurtzite GaN epilayers prepared by Metal Organic Chemical Vapor Deposition on 4H-SiC substrates of orientation vicinal to the (0001) (misorientation 0°, 3.4°, and 8°). Structural analysis using X-ray diffraction, defect-selective etching methods, and (High Resolution-) Transmission Electron Microscopy provides direct evidence for a higher number of defects in GaN epilayers grown on the 8° misoriented substrate compared to the 3.4° and 0° misoriented substrates. We found strong differences in morphology of the GaN epilayers and in type and density of the defects formed during growth on both vicinal and nominally exact oriented SiC substrates. The formation of clusters of defects and the non-uniform distribution of strain, resulting in preferential cracking of the GaN films along the [1120] direction, are both results of growth on misoriented substrates. Based on experimental results, the growth mechanism is discussed and a model explaining the defect formation is proposed.

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“…Due to the lack of natural GaN substrates, GaN-based LED structures are made typically on the (0001) c-plane sapphire substrates. 3,4 The interfacial energy difference between sapphire and GaN could cause large amount of dislocations and low crystal quality of the subsequently grown GaN layer. 5 The degraded quality of GaN layers presents intensive nonradiative recombination centers severely reducing the efficiency.…”

mentioning

confidence: 99%