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Selective area epitaxy of ultra-high density InGaN quantum dots by diblock copolymer lithography.

Liu G, Zhao H, Zhang J, Park JH, Mawst LJ, Tansu N - Nanoscale Res Lett (2011)

Bottom Line: The cylindrical-shaped nanopatterns were created on SiNx layers deposited on a GaN template, which provided the nanopatterning for the epitaxy of ultra-high density QD with uniform size and distribution.The InGaN/GaN QDs with density up to 8 × 1010 cm-2 are realized, which represents ultra-high dot density for highly uniform and well-controlled, nitride-based QDs, with QD diameter of approximately 22-25 nm.The photoluminescence (PL) studies indicated the importance of NH3 annealing and GaN spacer layer growth for improving the PL intensity of the SiNx-treated GaN surface, to achieve high optical-quality QDs applicable for photonics devices.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Optical Technologies, Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA 18015, USA. gul308@lehigh.edu.

ABSTRACT
Highly uniform InGaN-based quantum dots (QDs) grown on a nanopatterned dielectric layer defined by self-assembled diblock copolymer were performed by metal-organic chemical vapor deposition. The cylindrical-shaped nanopatterns were created on SiNx layers deposited on a GaN template, which provided the nanopatterning for the epitaxy of ultra-high density QD with uniform size and distribution. Scanning electron microscopy and atomic force microscopy measurements were conducted to investigate the QDs morphology. The InGaN/GaN QDs with density up to 8 × 1010 cm-2 are realized, which represents ultra-high dot density for highly uniform and well-controlled, nitride-based QDs, with QD diameter of approximately 22-25 nm. The photoluminescence (PL) studies indicated the importance of NH3 annealing and GaN spacer layer growth for improving the PL intensity of the SiNx-treated GaN surface, to achieve high optical-quality QDs applicable for photonics devices.

No MeSH data available.


PL comparison of planar SQW grown on (1) GaN with no surface treatment, (2) GaN with HF wet etching, and (3) GaN with SiNx deposition and HF etching.
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Figure 9: PL comparison of planar SQW grown on (1) GaN with no surface treatment, (2) GaN with HF wet etching, and (3) GaN with SiNx deposition and HF etching.

Mentions: To understand the impact of HF etching on the luminescence properties, the PL spectra comparison of InGaN single-QW samples grown on three different types of GaN template are shown in Figure 9. The active regions in all these samples consist of similar structure; 6 nm GaN barrier followed by 2.5 nm InGaN, and then 10 nm GaN cap layer. The comparison samples include the InGaN single QW grown on three templates as follows: (1) GaN template with no surface treatment (as reference sample), (2) GaN template with HF etching only, and (3) GaN template with SiNx deposition and HF wet etching. The data indicate that the HF etching does not lead to any detrimental effect on the InGaN QW grown afterward, while the SiNx deposition process leads to significant detrimental effect on the InGaN QW grown on top of the GaN template as indicated by the significant reduction in the PL intensity.


Selective area epitaxy of ultra-high density InGaN quantum dots by diblock copolymer lithography.

Liu G, Zhao H, Zhang J, Park JH, Mawst LJ, Tansu N - Nanoscale Res Lett (2011)

PL comparison of planar SQW grown on (1) GaN with no surface treatment, (2) GaN with HF wet etching, and (3) GaN with SiNx deposition and HF etching.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211431&req=5

Figure 9: PL comparison of planar SQW grown on (1) GaN with no surface treatment, (2) GaN with HF wet etching, and (3) GaN with SiNx deposition and HF etching.
Mentions: To understand the impact of HF etching on the luminescence properties, the PL spectra comparison of InGaN single-QW samples grown on three different types of GaN template are shown in Figure 9. The active regions in all these samples consist of similar structure; 6 nm GaN barrier followed by 2.5 nm InGaN, and then 10 nm GaN cap layer. The comparison samples include the InGaN single QW grown on three templates as follows: (1) GaN template with no surface treatment (as reference sample), (2) GaN template with HF etching only, and (3) GaN template with SiNx deposition and HF wet etching. The data indicate that the HF etching does not lead to any detrimental effect on the InGaN QW grown afterward, while the SiNx deposition process leads to significant detrimental effect on the InGaN QW grown on top of the GaN template as indicated by the significant reduction in the PL intensity.

Bottom Line: The cylindrical-shaped nanopatterns were created on SiNx layers deposited on a GaN template, which provided the nanopatterning for the epitaxy of ultra-high density QD with uniform size and distribution.The InGaN/GaN QDs with density up to 8 × 1010 cm-2 are realized, which represents ultra-high dot density for highly uniform and well-controlled, nitride-based QDs, with QD diameter of approximately 22-25 nm.The photoluminescence (PL) studies indicated the importance of NH3 annealing and GaN spacer layer growth for improving the PL intensity of the SiNx-treated GaN surface, to achieve high optical-quality QDs applicable for photonics devices.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Optical Technologies, Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA 18015, USA. gul308@lehigh.edu.

ABSTRACT
Highly uniform InGaN-based quantum dots (QDs) grown on a nanopatterned dielectric layer defined by self-assembled diblock copolymer were performed by metal-organic chemical vapor deposition. The cylindrical-shaped nanopatterns were created on SiNx layers deposited on a GaN template, which provided the nanopatterning for the epitaxy of ultra-high density QD with uniform size and distribution. Scanning electron microscopy and atomic force microscopy measurements were conducted to investigate the QDs morphology. The InGaN/GaN QDs with density up to 8 × 1010 cm-2 are realized, which represents ultra-high dot density for highly uniform and well-controlled, nitride-based QDs, with QD diameter of approximately 22-25 nm. The photoluminescence (PL) studies indicated the importance of NH3 annealing and GaN spacer layer growth for improving the PL intensity of the SiNx-treated GaN surface, to achieve high optical-quality QDs applicable for photonics devices.

No MeSH data available.