OMVPE Grown InAs Quantum Dots for Application in Nanostructured Photovoltaics

Hubbard, Seth M.; Wilt, David M.; Bailey, Sheila G.; Byrnes, D.; Raffaelle, Ryne P.

doi:10.1109/wcpec.2006.279378

Cited by 21 publications

(10 citation statements)

References 9 publications

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“…Details of the cell design and InAs QD growth parameters have been reported previously. 13 InAs QDs are formed using the StranskiKrastanov technique which takes advantage of the 7.8% compressive strain between InAs and GaAs substrate.…”

Section: Methodsmentioning

confidence: 99%

III-V quantum dot enhanced photovoltaic devices

et al. 2010

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State of the art photovoltaics exhibiting conversion efficiency in excess of 30% (1-sun) utilize epitaxially grown multijunction III-V materials. Increasing photovoltaic efficiency is critically important to the space power, and more recently, the terrestrial concentrator PV communitiesThe use of nanostructured materials within photovoltaic devices can enable improved efficiency, potentially in excess of the Shockley-Queisser limit. The addition of nanostructures such as quantum dots (QDs) to photovoltaic devices allows one to extend the absorption spectrum of the solar cell and "tune" the bandgap to the spectral conditions. Multi-junction (MJ) solar cells would benefit from the additional short-circuit current within the middle current-limiting (In)GaAs cell via QD spectral tuning. While QD tuning is a potentially direct approach to increased efficiency of MJ solar cells, it has been reported that significant improvements can be achieved using QDs to form an intermediate band within the bandgap of a suitable matrix.We will discuss the potential for QD photovoltaic devices and examine the challenges associated with multi-junction device growth with the inclusion of quantum dot arrays. GaAs p-i-n solar cells, with and without InAs QD superlattices are used to demonstrate the potential benefits of QDs. The unique challenges associated with the characterization of this type of device will also be presented. Using strain-balanced Stranski-Krastanov QD formation, we have demonstrated sub-gap photon collection and increased current in QD-enhanced GaAs solar cells containing up to 100 periods. Finally, we will discuss the opportunities that these devices hold for high photovoltaic conversion efficiency.

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Section: Methodsmentioning

confidence: 99%

III-V quantum dot enhanced photovoltaic devices

et al. 2010

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“…The structure of the single junction is shown in Figure 1. Details of the growth of the baseline and strain compensated QD solar cells have been described previously [6], [7], [8]. No anti-reflection coating (ARC) is deposited to minimize the number of variables for external quantum efficiency (EQE) measurements.…”

Section: Device Fabricationmentioning

confidence: 99%

Radiation effects on quantum dot enhanced solar cells

et al. 2012

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Radiation tolerance of quantum dot (QD) enhanced solar cells has been measured and modeled. GaAs solar cells enhanced with 10, 20, 40, 60, and 100X layers of strain compensated QDs are compared to baseline devices without QDs. Radiation resistance of the QD layers is higher than the bulk material. Increasing the number of QD layers does not lead to a systematic decrease in QD response throughout the course of radiation exposure. Additionally, InGaP/(In)GaAs/Ge triple junction solar cells with and without 10 layers of strain compensated QDs in the (In)GaAs triple junction solar cells are analyzed. Triple junction solar cells with QDs have a better resistance to Voc degradation but these samples have a degradation in Isc that leads to lower radiation resistance for power output.

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“…Substrates consisted of 350 !Jm thick GaAs oriented at 2° off the [100] direction toward the [110]. Growth conditions and optical properties of the OD have been reported previously [19]. A representative atomic force microscope (AFM) image of the optimal InAs dots is shown in Figure 2.…”

Section: Methodsmentioning

confidence: 91%

Short circuit current enhancement of GaAs solar cells using strain compensated InAs quantum dots

Hubbard

Bailey

Cress

et al. 2008

2008 33rd IEEE Photovolatic Specialists Conference

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Tensile strain compensation (SC) layers were introduced into GaAs p-i-n solar cells grown with a five stack of InAs quantum dots (QDs) within the i-region. The effects of strain within stacked layers of InAs quantum dots (QDs) were investigated using high resolution x-ray diffraction (HRXRD). Analysis of the HRXRD data shows that the average lattice strain is minimized for the optimal SC thickness. One sun air mass zero illuminated current voltage curvesshow that SC results in improved conversion efficiency and reduced dark current when compared to uncompensated devices. The strain compensated 5-layer QD solar cell shows a 0.9 mAlcm 2 increase in short circuit current compared to a baseline GaAs cell. Quantum efficiency measurements show this additional current results from photo-generated carriers within the quantum confined material.

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OMVPE Grown InAs Quantum Dots for Application in Nanostructured Photovoltaics

Cited by 21 publications

References 9 publications

III-V quantum dot enhanced photovoltaic devices

III-V quantum dot enhanced photovoltaic devices

Radiation effects on quantum dot enhanced solar cells

Short circuit current enhancement of GaAs solar cells using strain compensated InAs quantum dots

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