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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.

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PL enhancement study of SQW with different growth condition treatments.
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Figure 11: PL enhancement study of SQW with different growth condition treatments.

Mentions: Experiments were carried out to identify possible approaches to address the SiNx surface treatment issue, as illustrated in Figure 11. Different growth conditions were applied to the GaN templates that had been treated with SiNx deposition and HF etching, and the same InGaN QWs (6 nm GaN/2.5 nm InGaN/10 nm GaN) were grown afterwards. The PL spectra from InGaN QW directly grown on GaN template undergoing SiNx deposition and HF etching, without any additional growth treatment are shown in Figure 11 (Direct QW Growth). By annealing the GaN template under NH3 environment at 1070°C for 7 min, the single QW grown on the second sample has almost 40 times enhancement in the peak intensity at 420-nm emission. The third sample consisted of a 7-min GaN regrowth at 1070°C before the single-QW growth, and this sample exhibited additional approximately sevenfold improvement in peak intensity as compared to that of the second sample. The series of PL studies indicate that the GaN regrowth and the NH3 annealing condition before the QD/QW-active region growth could potentially lead to solutions for addressing the defect generated from the SiNx deposition on GaN templates. Future studies will involve the application of these procedures to the selective QD growth. Other future approaches by coupling the SAE InGaN QDs with surface plasmon based structures [65,66] will be of great interest for enhancing the radiative efficiency in LED devices.


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 enhancement study of SQW with different growth condition treatments.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 11: PL enhancement study of SQW with different growth condition treatments.
Mentions: Experiments were carried out to identify possible approaches to address the SiNx surface treatment issue, as illustrated in Figure 11. Different growth conditions were applied to the GaN templates that had been treated with SiNx deposition and HF etching, and the same InGaN QWs (6 nm GaN/2.5 nm InGaN/10 nm GaN) were grown afterwards. The PL spectra from InGaN QW directly grown on GaN template undergoing SiNx deposition and HF etching, without any additional growth treatment are shown in Figure 11 (Direct QW Growth). By annealing the GaN template under NH3 environment at 1070°C for 7 min, the single QW grown on the second sample has almost 40 times enhancement in the peak intensity at 420-nm emission. The third sample consisted of a 7-min GaN regrowth at 1070°C before the single-QW growth, and this sample exhibited additional approximately sevenfold improvement in peak intensity as compared to that of the second sample. The series of PL studies indicate that the GaN regrowth and the NH3 annealing condition before the QD/QW-active region growth could potentially lead to solutions for addressing the defect generated from the SiNx deposition on GaN templates. Future studies will involve the application of these procedures to the selective QD growth. Other future approaches by coupling the SAE InGaN QDs with surface plasmon based structures [65,66] will be of great interest for enhancing the radiative efficiency in LED devices.

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.


Related in: MedlinePlus