Investigation of electrically active defects in InGaAs quantum wire intermediate-band solar cells using deep-level transient spectroscopy technique

Saqri, Noor Alhuda Al; Felix, Jorlandio F.; Aziz, Mohsin; Kunets, Vasyl P.; Jameel, Dler; Taylor, David; Henini, M.; El-sadek, M.S. Abd; Furrow, C. S.; Ware, Morgan E.; Benamara, Mourad; Mortazavi, Mansour; Salamo, Gregory J.

doi:10.1088/1361-6528/28/4/045707

Cited by 12 publications

(5 citation statements)

References 55 publications

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“…Hence, for devices based on light absorption, a different structure design should be considered. We believe, such an improvement is necessary to be suggested because many research groups consider si -GaAs substrate as a basis for novel p - n -type both QD infrared photodetectors [ 11 – 13 ] and solar cells [ 15 ].…”

Section: Resultsmentioning

confidence: 99%

Bipolar Effects in Photovoltage of Metamorphic InAs/InGaAs/GaAs Quantum Dot Heterostructures: Characterization and Design Solutions for Light-Sensitive Devices

et al. 2017

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The bipolar effect of GaAs substrate and nearby layers on photovoltage of vertical metamorphic InAs/InGaAs in comparison with pseudomorphic (conventional) InAs/GaAs quantum dot (QD) structures were studied. Both metamorphic and pseudomorphic structures were grown by molecular beam epitaxy, using bottom contacts at either the grown n +-buffers or the GaAs substrate. The features related to QDs, wetting layers, and buffers have been identified in the photoelectric spectra of both the buffer-contacted structures, whereas the spectra of substrate-contacted samples showed the additional onset attributed to EL2 defect centers. The substrate-contacted samples demonstrated bipolar photovoltage; this was suggested to take place as a result of the competition between components related to QDs and their cladding layers with the substrate-related defects and deepest grown layer. No direct substrate effects were found in the spectra of the buffer-contacted structures. However, a notable negative influence of the n +-GaAs buffer layer on the photovoltage and photoconductivity signal was observed in the InAs/InGaAs structure. Analyzing the obtained results and the performed calculations, we have been able to provide insights on the design of metamorphic QD structures, which can be useful for the development of novel efficient photonic devices.

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Section: Resultsmentioning

confidence: 99%

Bipolar Effects in Photovoltage of Metamorphic InAs/InGaAs/GaAs Quantum Dot Heterostructures: Characterization and Design Solutions for Light-Sensitive Devices

et al. 2017

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“…thicker MBs or defect control strategies [28,29,87]) allowing to suppress strain-related defects generated near the QD layer and substrate/MB interface should be used. Simultaneously, the in-depth analysis of the effect of growth parameters on structural defects in multilayer stacks of QD is highly desirable [70,88]. We expect that these results and outcomes could foster further development of IR light-emitting devices based on InAs QDs embedded in In x Ga 1-x As layers with high percentages of indium.…”

Section: Time-dependent Pcmentioning

confidence: 96%

Defect influence on in-plane photocurrent of InAs/InGaAs quantum dot array: long-term electron trapping and Coulomb screening

et al. 2019

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Metamorphic InAs/In 0.15 Ga 0.85 As and InAs/In 0.31 Ga 0.69 As quantum dot (QD) arrays are known to be photosensitive in the telecommunication ranges at 1.3 and 1.55 μm, respectively; however, for photonic applications of these nanostructures, the effect of levels related to defects still needs in-depth investigation. We have focused on the influence of electron traps of defects on photocurrent (PC) in the plane of the QD array, studying by PC and deep level thermally stimulated current spectroscopy together with HRTEM and theoretical modeling. In the structures, a rich spectrum of electron trap levels of point defects EL6 (E c − 0.37 eV), EL7 (0.29-0.30 eV), EL8 (0.27 eV), EL9/M2 (0.22-0.23 eV), EL10/M1 (0.16 eV), M0 (∼0.11 eV) and three extended defects ED1/EL3 (0.52-0.54), ED2/EL4 (0.47-0.48 eV), ED3/EL5 (0.42-0.43 eV) has been identified. Among them, new defect levels undiscovered earlier in InAs/InGaAs nanostructures has been detected, in particular, EL8 and M0. The found electron traps are shown to affect a time-dependent PC at low temperatures. Besides a long-term kinetics due to trap charging, a prolonged PC decrement versus time is measured under constant illumination. The decrement is interpreted to be related to a Coulomb screening of the conductivity channel by the electrons captured in the QD interface traps. The decrement is well fitted by allometric exponents, which means many types of traps involved in electron capturing. This study provides new findings into the mechanism of in-plane PC of QD arrays, showing a crucial importance of growth-related defects on photoresponsivity at low temperatures.

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“…However, the above techniques allow to visualize only extended defects without information about the associated trap level states. Unlike the GaAs-based QD structures, highly investigated earlier [17][18][19][20][21][22][23], at present there are only a few photoelectric studies of defects in metamorphic In(Ga) As/InGaAs ones. DLTS spectra of InAs/In 0.15 Ga 0.85 As QD structures by Rimada et al [24] have shown two peaks associated with point defects (PDs) along with two bands associated with extended defects related to threading dislocations and V-shaped defects generated, respectively, at the lower InGaAs/GaAs interface [25] and in the QD plane [25,26].…”

Section: Introductionmentioning

confidence: 99%

Deep levels in metamorphic InAs/InGaAs quantum dot structures with different composition of the embedding layers

Golovynskyi

Datsenko

Seravalli

et al. 2017

Semicond. Sci. Technol.

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Deep levels in metamorphic InAs/In x Ga 1−x As quantum dot (QD) structures are studied with deep level thermally stimulated conductivity (TSC), photoconductivity (PC) and photoluminescence (PL) spectroscopy and compared with data from pseudomorphic InGaAs/ GaAs QDs investigated previously by the same techniques. We have found that for a low content of indium (x=0.15) the trap density in the plane of self-assembled QDs is comparable or less than the one for InGaAs/GaAs QDs. However, the trap density increases with x, resulting in a rise of the defect photoresponse in PC and TSC spectra as well as a reduction of the QD PL intensity. The activation energies of the deep levels and some traps correspond to known defect complexes EL2, EL6, EL7, EL9, and EL10 inherent in GaAs, and three traps are attributed to the extended defects, located in InGaAs embedding layers. The rest of them have been found as concentrated mainly close to QDs, as their density in the deeper InGaAs buffers is much lower. This an important result for the development of light-emitting and light-sensitive devices based on metamorphic InAs QDs, as it is a strong indication that the defect density is not higher than in pseudomorphic InAs QDs.

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Investigation of electrically active defects in InGaAs quantum wire intermediate-band solar cells using deep-level transient spectroscopy technique

Cited by 12 publications

References 55 publications

Bipolar Effects in Photovoltage of Metamorphic InAs/InGaAs/GaAs Quantum Dot Heterostructures: Characterization and Design Solutions for Light-Sensitive Devices

Bipolar Effects in Photovoltage of Metamorphic InAs/InGaAs/GaAs Quantum Dot Heterostructures: Characterization and Design Solutions for Light-Sensitive Devices

Defect influence on in-plane photocurrent of InAs/InGaAs quantum dot array: long-term electron trapping and Coulomb screening

Deep levels in metamorphic InAs/InGaAs quantum dot structures with different composition of the embedding layers

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