OMVPE of InAs quantum dots on an InGaP surface

Forbes, David V.; Podell, Adam; Slocum, Michael A.; Polly, Stephen J.; Hubbard, Seth M.

doi:10.1016/j.mssp.2013.02.011

Cited by 9 publications

(5 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…39 Thus, for the InAs/GaAs QD-IBSC at 300 K, although the ground state tunneling rate reaches 8 Â 10 6 s À1 at 50 kV/cm, the thermal escape (10 11 s À1 ) will limit TSPA under concentrated illumination. In order to enable TSPA to be dominant at room temperature, barrier modifications with wide band gap material including InGaP 40,41 or AlGaAs 42,43 are being considered for the IBSC design to suppress the thermal coupling between the IB and CB at the room temperature. The radiative recombination (10 8 -10 9 s À1 ) also reduces the efficiency of TSPA in InAs/GaAs QD.…”

Section: A Simulationmentioning

confidence: 99%

Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells

Polly

Hellstroem

Slocum

et al. 2017

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

Carrier escape and recombination from quantum dot (QD) states reduce the probability of two-step photon absorption (TSPA) by decreasing the available carrier population in the intermediate band (IB). In order to optimize the second photon absorption for future designs of quantum dot embedded intermediate band solar cells, the presented study combined the results of simulations and experiments to quantify the effect of electric field on the barrier height and the carrier escape from the QDs in InAs/GaAs quantum dot solar cells with five-layer QD superlattices. The electric field dependent effective barrier heights for ground state electrons were calculated using eight band kÁp theory at short circuit conditions. With an increase in electric field surrounding the QDs from 5 kV/cm to 50 kV/cm, the effective barrier height of the ground state electrons was reduced from 147 meV to 136 meV, respectively. Thus, the increasing electric field not only exponentially enhances the ground state electron tunneling rate (effectively zero at 5 kV/cm and 7.9 Â 10 6 s À1 at 50 kV/cm) but also doubles the thermal escape rate (2.2 Â 10 11 s À1 at 5 kV/cm and 4.1 Â 10 11 s À1 at 50 kV/cm). Temperature-dependent external quantum efficiency measurements were performed to verify that the increasing electric field decreases the effective barrier height. Additionally, the electric field dependent radiative lifetimes of the ground state were characterized with time-resolved photoluminescence experiments. This study showed that the increasing electric field extended the radiative recombination lifetime in the ground state of the QDs as a consequence of the reduced wave-function overlap between the electrons and holes. The balance of carrier escape and recombination determines the probability of TSPA. Published by AIP Publishing.

show abstract

Section: A Simulationmentioning

confidence: 99%

Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells

Polly

Hellstroem

Slocum

et al. 2017

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…Clearly, using a barrier material with an energy bandgap around 1.95 eV is one of the approaches to be followed. QDs embedded in a wide band gap material such as AlGaAs or InGaP have been studied as potential candidates to provide such ideal band structure [4][5][6][7][8][9]. In the case of AlGaAs used as barrier material or interlayer, up to now, the introduction of QDs not only did not improve the device performance, but led to a reduction of the solar cells' efficiencies.…”

Section: Introductionmentioning

confidence: 99%

Panning ideal In(Ga)As(P)/InGaP quantum dot structures for intermediate band solar cells

Weiner,

Jakomin,

Kawabata

et al. 2023

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

The In(Ga)As(P)/InGaP quantum dot system has been investigated for quantum dot intermediate band solar cells. In order to obtain optical transition energies compatible with the ideal ones required for the device record performance, namely: 1.95 eV, 1.24 eV and 0.7 eV, first disordered InGaP with a bandgap of 1.91 eV as the barrier material has been obtained. Then InAs QDs nucleated at 490 °C, 1.32 MLs thick, covered by a 3-4 nm GaAs capping layer and In-flushed provided radiation emission in the energy interval between 1.15 eV and 1.35 eV, fully compatible with the ideal 1.24 eV. The 4 nm capped structures have been proven to exhibit a stronger PL emission at 1.24 eV. Nominal InAs quantum dots suffer a pronounced incorporation of Ga, a consequence of In/Ga intermixing at their capping layer and barrier interfaces. An As/P intermixing also occurs at the quantum dot- barrier interface. The encouraging results herald further improvement of quantum dot intermediate band solar cell’s performance.

show abstract

“…There are some studies on InAs QDs grown on In 0.49 Ga 0.51 P latticedmatched to GaAs, grown by solid-source molecular beam epitaxy [15], [16] or by vapor phase epitaxy [17]. It has been found that there is intermixing between the InGaP spacers and the InAs QDs, leading to the presence of InGaAsP alloys, which modify the optical properties of the dots [15].…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. [17] the QDs resulted larger than the typical size for InAs/GaAs, which is an undesirable effect for IBSC purposes [18]. To avoid intermixing and increase the electron confinement in the dots, in Refs.…”

Section: Introductionmentioning

confidence: 99%

Wide-Bandgap InAs/InGaP Quantum-Dot Intermediate Band Solar Cells

Ramiro

Villa

Lam

et al. 2015

IEEE J. Photovoltaics

View full text Add to dashboard Cite

Abstract-Current prototypes of quantum-dot intermediate band solar cells suffer from voltage reduction due to the existence of carrier thermal escape. An enlarged sub-bandgap E L would not only minimize this problem, but would also lead to a bandgap distribution that exploits more efficiently the solar spectrum. In this work we demonstrate InAs/InGaP QD-IBSC prototypes with the following bandgap distribution: E G = 1.88 eV, E H = 1.26 eV and E L > 0.4 eV. We have measured, for the first time in this material, both the interband and intraband transitions by means of photocurrent experiments. The activation energy of the carrier thermal escape in our devices has also been measured. It is found that its value, compared to InAs/GaAs-based prototypes, does not follow the increase in E L . The benefits of using thin AlGaAs barriers before and after the quantum-dot layers are analyzed.

show abstract

OMVPE of InAs quantum dots on an InGaP surface

Cited by 9 publications

References 27 publications

Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells

Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells

Panning ideal In(Ga)As(P)/InGaP quantum dot structures for intermediate band solar cells

Wide-Bandgap InAs/InGaP Quantum-Dot Intermediate Band Solar Cells

Contact Info

Product

Resources

About