Trap-Induced Dispersive Transport and Dielectric Loss in PbS Nanoparticle Films

AbstractIn this work, we investigate the electrical and dielectric response of lead sulfide (PbS) nanoparticle (NP) films with impedance spectroscopy. In particular, the influence of the ligand passivation on the surface trap state density of PbS NPs is demonstrated by comparing two different types of ligands: ethane-1,2-dithiol (EDT) and 3-sulfanylpropanoic acid (MPA). We observe that the MPA treatment passivates the PbS surface more efficiently than EDT. By analyzing the dielectric loss spectra, we are able to visualize shallow trap states in the bulk of PbS-EDT films and correlate this with the dispersive response observed in the impedance spectra. Evidence of deep trap states is revealed for both PbS-EDT and PbS-MPA diodes. Under illumination, the PbS-MPA and PbS-EDT films demonstrate almost identical trap profiles, showing solely the deep trap state densities. We conclude that the deep traps are related to the stoichiometry of the PbS NPs.

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Deep Surface Trap States at ZnO Nanorods Arrays

MRS Proceedings ◽

10.1557/opl.2014.685 ◽

2014 ◽

Vol 1672 ◽

Cited By ~ 1

Author(s):

Christa Bünzli ◽

David Parker ◽

Kieren Bradley ◽

David J. Fermín

Keyword(s):

Zno Nanorods ◽

Sharp Decrease ◽

Deep Trap ◽

Flat Band ◽

Flat Band Potential ◽

Trap States ◽

Surface Trap ◽

Deep Surface ◽

Deep Electron Trap ◽

Lock In

ABSTRACTDeep surface trap states present in hydrothermally grown ZnO nanorod (NR) arrays are monitored by photoelectrochemical and impedance spectroscopy. NR arrays were grown on a thin compact ZnO film deposited by pulsed laser deposition. Photocurrent responses upon square-wave illumination and lock-in detection of the as-grown NR arrays in the presence of Na2SO3 at pH 10 were characterized by a complex potential dependence indicating the presence of deep trap states. At a given frequency of light perturbation, the photocurrent amplitude increases as the potential bias is shifted towards values more positive than the flat band potential. Increasing the potential further than 0.8 V positive to the flat band potential leads to a decrease in the photocurrent amplitude. The potential of maximum photocurrent amplitude overlaps with a sharp decrease in the interfacial capacitance. The dependence of the photocurrent amplitude on bias potential strongly suggests the presence of deep electron trap states. The effect of the deep trap states are minimized by annealing of the NR arrays in air at 340° C.

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Ultrahigh sensitivity of methylammonium lead tribromide perovskite single crystals to environmental gases

Science Advances ◽

10.1126/sciadv.1600534 ◽

2016 ◽

Vol 2 (7) ◽

pp. e1600534 ◽

Cited By ~ 186

Author(s):

Hong-Hua Fang ◽

Sampson Adjokatse ◽

Haotong Wei ◽

Jie Yang ◽

Graeme R. Blake ◽

...

Keyword(s):

Single Crystals ◽

Surface Recombination ◽

State Density ◽

Limiting Factors ◽

Surface Recombination Velocity ◽

Photoluminescence Intensity ◽

Trap State ◽

Surface Trap ◽

Design And Optimization ◽

Surface Recombination Rate

One of the limiting factors to high device performance in photovoltaics is the presence of surface traps. Hence, the understanding and control of carrier recombination at the surface of organic-inorganic hybrid perovskite is critical for the design and optimization of devices with this material as the active layer. We demonstrate that the surface recombination rate (or surface trap state density) in methylammonium lead tribromide (MAPbBr3) single crystals can be fully and reversibly controlled by the physisorption of oxygen and water molecules, leading to a modulation of the photoluminescence intensity by over two orders of magnitude. We report an unusually low surface recombination velocity of 4 cm/s (corresponding to a surface trap state density of 108cm−2) in this material, which is the lowest value ever reported for hybrid perovskites. In addition, a consistent modulation of the transport properties in single crystal devices is evidenced. Our findings highlight the importance of environmental conditions on the investigation and fabrication of high-quality, perovskite-based devices and offer a new potential application of these materials to detect oxygen and water vapor.

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Determination of the Trap State Density Differences in Hydrogenated Amorphous Silicon-Germanium Alloys

Journal of Materials Research ◽

10.1557/jmr.2005.0014 ◽

2005 ◽

Vol 20 (1) ◽

pp. 48-53

Author(s):

M. Boshta ◽

K. Bärner ◽

R. Braunstein ◽

B. Alavi ◽

B. Nelson

Keyword(s):

Silicon Germanium ◽

State Density ◽

Trap States ◽

Trap State ◽

Thermoelectric Effects ◽

Time Resolved ◽

Amorphous Silicon Germanium ◽

First Time ◽

Hydrogenated Amorphous

Time-resolved photo- and thermoelectric effects (TTE) were used to determine simultaneously trap levels and trap state density differences in amorphous (a-SiGe:H) samples. In particular, the trap state density differences are obtained from the decay of the ambipolar charge distribution (i.e., stage II of the TTE transients). This type of spectroscopy has been applied for the first time to a-SiGe:H samples, and indeed trap states that seem to relate to concentration fluctuations, that is, Si(Ge) and Ge(Si) clusters, are observed.

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Origin of surface trap states in CdS quantum dots: relationship between size dependent photoluminescence and sulfur vacancy trap states

Physical Chemistry Chemical Physics ◽

10.1039/c4cp04761c ◽

2015 ◽

Vol 17 (4) ◽

pp. 2850-2858 ◽

Cited By ~ 123

Author(s):

Aisea Veamatahau ◽

Bo Jiang ◽

Tom Seifert ◽

Satoshi Makuta ◽

Kay Latham ◽

...

Keyword(s):

Quantum Dots ◽

Quantum Dot ◽

Trap States ◽

Cds Quantum Dots ◽

Trap State ◽

Sulfur Vacancy ◽

Surface Trap ◽

Trapped Electrons ◽

Size Dependent ◽

Cds Quantum Dot

Trap state emission mainly originates from deep trapped electrons at surface Cd with sulfur vacancy sites of CdS quantum dot.

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Facet-Dependent Surface Trap States and Carrier Lifetimes of Silicon

Nano Letters ◽

10.1021/acs.nanolett.9b05237 ◽

2020 ◽

Vol 20 (3) ◽

pp. 1952-1958 ◽

Cited By ~ 2

Author(s):

Chih-Shan Tan ◽

Yicheng Zhao ◽

Rong-Hao Guo ◽

Wei-Tsung Chuang ◽

Lih-Juann Chen ◽

...

Keyword(s):

Trap States ◽

Surface Trap ◽

Carrier Lifetimes

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Detection of Interfaces States Correlated with Layer-by-Layer Oxidation on Si(100)

MRS Proceedings ◽

10.1557/proc-592-33 ◽

1999 ◽

Vol 592 ◽

Author(s):

T. Hattori ◽

H. Nohira ◽

Y Teramoto ◽

N. Watanabe

Keyword(s):

Surface Roughness ◽

Oxide Film ◽

Film Thickness ◽

Interface State ◽

State Density ◽

Layer By Layer ◽

Oxide Film Thickness ◽

Maximum Value ◽

State Densities ◽

Atomically Flat

ABSTRACTThe interface state densities near the midgap were measured with the progress of oxidation of atomically flat Si(100) surface. It was found that the interface state distribution in Si bandgap changes periodically with the progress of oxidation. Namely, the interface-state density near the midgap of Si exhibits drastic decrease at oxide film thickness where the surface roughness of oxide film takes its minimum value, while that does not exhibit decrease at the oxide film thickness where the surface roughness takes its maximum value. In order to minimize interface state densities the oxide film thickness should be precisely controlled to within an accuracy of 0.02 nm.

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Improvement of Local Deep Level Transient Spectroscopy for Microscopic Evaluation of SiO2/4H-SiC Interfaces

Materials Science Forum ◽

10.4028/www.scientific.net/msf.924.289 ◽

2018 ◽

Vol 924 ◽

pp. 289-292

Author(s):

Yuji Yamagishi ◽

Yasuo Cho

Keyword(s):

Deep Level ◽

Interface State ◽

State Density ◽

Trap States ◽

Accurate Analysis ◽

Microscopic Evaluation ◽

Transient Spectroscopy ◽

Capacitance Transient ◽

Full Waveforms ◽

Dimensional Mapping

We demonstrate our new local deep level spectroscopy system improved for more accurate analysis of trap states at SiO2/4H-SiC interfaces. Full waveforms of the local capacitance transient with the amplitude of attofarads and the time scale of microseconds were obtained and quantitatively analyzed. The local energy distribution of interface state density in the energy range of EC − Eit = 0.31–0.38 eV was obtained. Two-dimensional mapping of the interface states showed inhomogeneous contrasts with the lateral spatial scale of several hundreds of nanometers, suggesting that the physical origin of the trap states at SiO2/SiC interfaces is likely to be microscopically clustered.

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