Probing electronic defect states in manganite/SrTiO3 heterostructures by surface photovoltage spectroscopy

Beyreuther, Elke; Thiessen, A.; Becherer, J.; Grafström, S.; Dörr, K.; Eng, Lukas M.

doi:10.1016/j.mseb.2010.12.014

Cited by 7 publications

(10 citation statements)

References 24 publications

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“…They reported mainly STO related states to be responsible for observed photovoltages ( i.e. optimization should focus on STO), 149 however, specific thin film related states were detected in accordance with another work. 150 Such an optimization of undoped STO can be achieved via self doping, i.e.…”

Section: Photovoltagesupporting

confidence: 81%

“…Schottky or p-n junctions) for the generation of photovoltages (for more information on dye sensitized solar cells, the reader is referred to the review by Suzuki et al [142]). Despite the properties of heterojunctions cannot be solely ascribed to one constituent, in the present review, STO heterojunctions with different top layers are discussed, ranging from organic or metallic coatings to inorganic and oxide top layers, where throughout, photovoltages of several 100 [149], however, specific thin film related states were detected as well in another work [150]. Such an optimization of undoped STO can be achieved via self doping, i.e.…”

Section: Low Temperature Effectsmentioning

confidence: 96%

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Photoinduced electronic and ionic effects in strontium titanate

et al. 2021

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Section: Photovoltagesupporting

confidence: 81%

Section: Low Temperature Effectsmentioning

confidence: 96%

Photoinduced electronic and ionic effects in strontium titanate

et al. 2021

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“…In fact, this effect occurred only once, as discussed in the supplement 44 (figure S1). Second, the transients represent essential complementary data for comparing the electronic properties of the samples, since for SrTiO 3 -based heterostructures the a full explanation and interpretation of the purely spectral data alone is commonly not unambigously possible 40 . …”

Section: B Surface Photovoltage Measurementsmentioning

confidence: 99%

“…Part of the super-bandgap features might directly originate from higher optical transitions (cf. 49), others may stem from the convolution of the SPV spectrum with multi-level relaxation processes, which are typical for SrTiO 3 under super-bandgap excitation 39,40 , or persistent photoconductivity effects 50 .…”

Section: A General Featuresmentioning

confidence: 99%

Conducting and insulating LaAlO3/SrTiO3 interfaces: A comparative surface photovoltage investigation

Beyreuther

Paparo

Thiessen

et al. 2013

Journal of Applied Physics

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Surface photovoltage (SPV) spectroscopy, which is a versatile method to analyze the energetic distribution of electronic defect states at surfaces and interfaces of wide-bandgap semiconductor (hetero-)structures, is applied to comparatively investigate heterostructures made of 5-unit-cell-thick LaAlO 3 films grown either on TiO 2 -or on SrO-terminated SrTiO 3 . As shown in a number of experimental and theoretical investigations in the past, these two interfaces exhibit dramatically different properties with the first being conducting and the second insulating.Our present SPV investigation reveals clearly distinguishable interface defect state distributions for both configurations when interpreted within the framework of a classical semiconductor band scheme. Furthermore, bare SrTiO 3 crystals with TiO 2 or mixed SrO/TiO 2 terminations show similar SPV spectra and transients as do LaAlO 3 -covered samples with the respective termination of the SrTiO 3 substrate. This is in accordance with a number of recent works that stress the decisive role of SrTiO 3 and the minor role of LaAlO 3 with respect to the electronic interface properties.

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“…As a photovoltaic component, STO crystals have a large advantage to be transparent with visible light, which opens new usage or functionality that is fundamentally impossible by silicon‐based solar cells. Concerning the photo‐induced phenomena in technology, generation of the photovoltage is the most fundamental optical response, and therefore extensive studies have been carried out to clarify mechanisms in the surface photovoltage (SPV) effect . The SPV is an effect generated by photo‐induced electron–hole pairs near a surface or an interface.…”

mentioning

confidence: 99%

Tailoring Photovoltage Response at SrRuO₃/SrTiO₃ Heterostructures

Yukawa

Yamamoto

Akikubo

et al. 2016

Adv Materials Inter

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band diagrams and the optical responses were evaluated by soft X-ray photoelectron spectroscopy (PES) that selectively probes either the SRO overlayer or the STO substrate. Space-charge layers of the STO crystal are controlled between the accumulation-type and the depletion-type by the surface/interface conditions. Then, amount of the photovoltage and lifetime of the photo-excited carriers in the SRO/STO system were traced by the time-resolved measurement. We show that the SPV effect in an STO crystal was drastically dependent on the initial electrostatic potential structure at the SRO/STO interface that is understood from the bulk-band bending effect.The optical responses of the surface/interface systems were induced by irradiation of the second harmonic generation of a Ti:sapphire laser and were monitored by the soft-X ray core-level PES using synchrotron radiation (SR). The time-resolved measurements at the delay time (t) were made by the pump(laser)probe(SR) method. [14] Figure 1a shows time-resolved Sr 3d core-level spectra of the bare STO surface and the SRO/STO interfaces with different SRO thicknesses taken before and after the light irradiation. Taking the Sr 3d 5/2 peak position before the optical pumping as the energy reference, the energy shifts of 15, 180, and 90 meV in binding energies with an uncertainty of ±25 meV were obtained for the STO, SRO(2 ML)/STO, and SRO(4 ML)/ STO surfaces, respectively. The spectral peaks obviously shift to the higher binding energies after the photo-excitation for the SRO/STO heterojunctions but not for the bare STO surface. To assign the energy shift at the SRO/STO interface, time-resolved measurements were made for core-level spectra of Sr 3d and Ti 2p, as shown in Figure 1b. After the optical pumping, both the Sr and Ti spectral peaks shift by the same amount of value (105 ± 25 meV) to the higher binding energy. While the Sr signals originate from both the SRO overlayer and the STO substrate (see the Supporting Information), Ti peak is only from the STO substrate. Therefore, the PES signals of the Ti peak are suppressed as in Figure 1b. Focusing on the Sr core-level peak, one finds a lack of observable broadening of the Sr 3d peak before and after the optical excitation. These facts indicate the simultaneous energy shifts of electronic bands in SRO and STO as well as the drastic change of optical response of the STO substrate with the SRO overlayers.The photo-induced phenomena result from dynamics of the photo-excited carriers that are governed by electronic potential induced by the interface electronic structure. To clarify the electric potential, core-level peak positions and the valence band maxima (VBMs) were obtained. Figure 2a shows a collection of valence band photoelectron spectra of the STO surface and SRO/STO interfaces with 2 ML-and 4 ML-thick SRO films. On Strontium titanate (SrTiO 3 : STO) has been regarded as one of the key materials for the metal oxide industry owing to its chemical stabilities, non-toxic natures, and exotic electron correlation effec...

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Probing electronic defect states in manganite/SrTiO3 heterostructures by surface photovoltage spectroscopy

Cited by 7 publications

References 24 publications

Photoinduced electronic and ionic effects in strontium titanate

Photoinduced electronic and ionic effects in strontium titanate

Conducting and insulating LaAlO3/SrTiO3 interfaces: A comparative surface photovoltage investigation

Tailoring Photovoltage Response at SrRuO₃/SrTiO₃ Heterostructures

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Probing electronic defect states in manganite/SrTiO3 heterostructures by surface photovoltage spectroscopy

Cited by 7 publications

References 24 publications

Photoinduced electronic and ionic effects in strontium titanate

Photoinduced electronic and ionic effects in strontium titanate

Conducting and insulating LaAlO3/SrTiO3 interfaces: A comparative surface photovoltage investigation

Tailoring Photovoltage Response at SrRuO3/SrTiO3 Heterostructures

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Tailoring Photovoltage Response at SrRuO₃/SrTiO₃ Heterostructures