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Quantum-size-controlled photoelectrochemical fabrication of epitaxial InGaN quantum dots

Nano Letters

Xiao, Xiaoyin; Fischer, Arthur J.; Wang, George T.; Lu, Ping; Koleske, Daniel; Coltrin, Michael E.; Wright, Jeremy B.; Liu, Sheng; Brener, Igal; Subramania, Ganapathi S.; Tsao, Jeffrey Y.

We demonstrate a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10 nm size regime: quantum-size-controlled photoelectrochemical (QSC-PEC) etching. We show that quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and that the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength. Low-temperature photoluminescence from ensembles of such QDs have peak wavelengths that can be tunably blue shifted by 35 nm (from 440 to 405 nm) and have line widths that narrow by 3 times (from 19 to 6 nm).

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TYPE Journal Article YEAR 2014
ScopusOSTIDOI

The Energy Frontier Research Center for Solid-State Lighting Science: Exploring New Materials Architectures and Light Emission Phenomena

Journal of Physical Chemistry C

Coltrin, Michael E.; Subramania, Ganapathi S.; Tsao, Jeffrey Y.; Wang, George T.; Wierer, Jonathan J.; Wright, Jeremy B.; Armstrong, Andrew A.; Brener, Igal; Chow, Weng W.; Crawford, Mary H.; Fischer, Arthur J.; Koleske, Daniel; Martin, James E.; Rohwer, Lauren E.S.

Abstract not provided.

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TYPE Journal Article YEAR 2014
OSTIDOI

Contribution of deep-level defects to decreasing radiative efficiency of InGaN/GaN quantum wells with increasing emission wavelength

Applied Physics Express

Armstrong, Andrew A.; Crawford, Mary H.; Koleske, Daniel

Deep-level optical spectroscopy (DLOS) and photoluminescence (PL) were used to understand the role of defects in reducing the internal quantum efficiency (IQE) of InxGa1-xN/GaN multiple quantum wells (MQWs) as the emission wavelength increased from approximately 450 to 530 nm, i.e., the "green gap". DLOS studies of light emitting diodes (LEDs) identified QW defects whose concentration increased significantly with increasing x. The effect of increased QW defect density on IQE was assessed by examining the PL of MQW samples. Green-emitting MQWs had lower IQE and required higher pump power to reach peak IQE, corroborating the important impact of enhanced non-radiative recombination at defects. © 2014 The Japan Society of Applied Physics.

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TYPE Journal Article YEAR 2014
OSTIScopus

Semi-polar GaN Materials Technology for High IQE Green LEDs

Koleske, Daniel; Lee, Stephen R.; Crawford, Mary H.; Coltrin, Michael E.

The goal of this NETL funded program was to improve the IQE in green (and longer wavelength) nitride- based LEDs structures by using semi-polar GaN planar orientations for InGaN multiple quantum well (MQW) growth. These semi-polar orientations have the advantage of significantly reducing the piezoelectric fields that distort the QW band structure and decrease electron-hole overlap. In addition, semipolar surfaces potentially provide a more open surface bonding environment for indium incorporation, thus enabling higher indium concentrations in the InGaN MQW. The goal of the proposed work was to select the optimal semi-polar orientation and explore wafer miscuts around this orientation that produced the highest quantum efficiency LEDs. At the end of this program we had hoped to have MQWs active regions at 540 nm with an IQE of 50% and an EQE of 40%, which would be approximately twice the estimated current state-of-the-art.

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TYPE SAND Report YEAR 2013
DOIOSTI
Results 51–100 of 203
Results 51–100 of 203