Pit formation in GaInN quantum wells

Chen, Y.; Takeuchi, Tetsuya; Amano, Hiroshi; Akasaki, Isamu; Yamada, Noriko; Kaneko, Y.; Wang, Shih-Yuan

doi:10.1063/1.120853

Cited by 252 publications

(182 citation statements)

References 9 publications

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“…For InGaN and GaN films V-shaped pinholes are commonly observed. 2,15 Pinholes are open hexagonal inverted pyramids defined by the six ͕10-11͖ planes, and are reported to originate from either threading dislocations, 15 stacking mismatch boundaries induced by stacking faults due to strain relaxation 16 or from slow growth rate on polar ͑10-11͒ planes induced by impurity poisoning of growth steps or any development of surface roughness during growth. 17 Liliental-Weber et al 17 have studied the formation of V-shape pinholes, related to V-shape facets in ͑10-11͒ polar planes and nanotubes with ͑10-10͒ facets, in tensile strained GaN films.…”

Section: Discussionmentioning

confidence: 99%

Study of pinholes and nanotubes in AlInGaN films by cathodoluminescence and atomic force microscopy

Herrera

Cremades

Piqueras

et al. 2004

Journal of Applied Physics

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Cathodoluminescence ͑CL͒ in the scanning electron microscope and atomic force microscopy ͑AFM͒ have been used to study the formation of pinholes in tensile and compressively strained AlInGaN films grown on Al 2 O 3 substrates by plasma-induced molecular beam epitaxy. Nanotubes, pits, and V-shaped pinholes are observed in a tensile strained sample. CL images show an enhanced emission around the pits and a lower intensity at the V-shaped pinholes. Rounded pinholes appear in compressively strained samples in island-like regions with higher In concentration. The grain structure near the pinholes is resolved by AFM.

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Section: Discussionmentioning

confidence: 99%

Study of pinholes and nanotubes in AlInGaN films by cathodoluminescence and atomic force microscopy

Herrera

Cremades

Piqueras

et al. 2004

Journal of Applied Physics

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“…7 Another suggested mechanism involves the formation of pits at the dislocation surface termination. 12 These topographical V-defects may induce a screening of the threading dislocations for carriers thanks to a potential barrier located in their vicinity. 13 Besides an improved structural quality, the InGaN UL has been proposed to affect the band profile due to pinning of the Fermi level at the InGaN/ GaN interface, which in turn reduces the built-in electric field in the QWs and thus leads to an increase in the QW radiative efficiency.…”

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confidence: 99%

Burying non-radiative defects in InGaN underlayer to increase InGaN/GaN quantum well efficiency

Haller

Carlin

Jacopin

et al. 2017

Applied Physics Letters

108

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The insertion of an InGaN underlayer (UL) is known to strongly improve the performance of InGaN/GaN quantum well (QW) based blue light emitting diodes (LEDs). However, the actual physical mechanism responsible for it is still unclear. We thus conduct a systematic study and investigate different hypotheses. To this aim, InGaN/GaN single (S) QWs are grown on sapphire and GaN free-standing substrates with or without InGaN UL. This allows us to conclude that (i) improvement of LED performance is due to a higher internal quantum efficiency of the InGaN/GaN SQW and (ii) reduction of structural defects is not at play. Furthermore, we show that neither the surface morphology nor the strain of the top GaN layer before the growth of the QW is affected by the InGaN UL. Finally, we find that the beneficial effect of the InGaN UL is still present after 100 nm of GaN. This result combined with band structure modelling rules out the hypothesis of higher QW oscillator strength induced by a reduction of the internal electric field due to band bending. In conclusion, we demonstrate that the increase in InGaN/GaN QW efficiency is the consequence of a reduction of non-radiative recombination centers in the QW itself, independent of the dislocation density.

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“…10 Some researchers have observed that V-shape defects are connected to the TDs at their bottom. 16,17 To investigate the morphology of the InGaN/GaN MQWs structure grown on both planar and vicinal substrates, SEM images were employed. Fig.…”

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confidence: 99%

Morphological dependent Indium incorporation in InGaN/GaN multiple quantum wells structure grown on 4° misoriented sapphire substrate

Jiang

Zhang

et al. 2016

AIP Advances

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The epitaxial layers of InGaN/GaN MQWs structure were grown on both planar and vicinal sapphire substrates by metal organic chemical vapor deposition. By comparing the epitaxial layers grown on planar substrate, the sample grown on 4° misoriented from c-plane toward <101̄0> m-plane substrate exhibited many variations both on surface morphology and optical properties according to the scanning electronic microscopy and cathodoluminescence (CL) spectroscopy results. Many huge steps were observed in the misoriented sample and a large amount of V-shape defects located around the boundary of the steps. Atoms force microscopy images show that the steps were inclined and deep grooves were formed at the boundary of the adjacent steps. Phase separation was observed in the CL spectra. CL mapping results also indicated that the deep grooves could effectively influence the localization of Indium atoms and form an In-rich region.

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Pit formation in GaInN quantum wells

Cited by 252 publications

References 9 publications

Study of pinholes and nanotubes in AlInGaN films by cathodoluminescence and atomic force microscopy

Study of pinholes and nanotubes in AlInGaN films by cathodoluminescence and atomic force microscopy

Burying non-radiative defects in InGaN underlayer to increase InGaN/GaN quantum well efficiency

Morphological dependent Indium incorporation in InGaN/GaN multiple quantum wells structure grown on 4° misoriented sapphire substrate

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