Analysis of the surface photovoltaic effect in photoconductors: CdS

Maltby, J R; Reed, C E; Scott, C.G.

doi:10.1016/0039-6028(75)90236-8

Cited by 18 publications

(5 citation statements)

References 18 publications

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“…(2.26) is dominated by mobile, rather than static, charges. However, it may be very signi®cant in the depletion regime [35].…”

Section: Surface Space Charge Regionmentioning

confidence: 99%

“…Consider, for example, the SPV in a CdS sample with bulk acceptor and donor states, as well as surface states situated at varying energies within the bandgap, studied by Maltby et al [35] Fig. 12(a) features the SPV as a function of the fractional excess carrier density, Á n , Fig for three different surface state positions, whereas Fig.…”

Section: Super-bandgap Spvmentioning

confidence: 99%

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Surface photovoltage phenomena: theory, experiment, and applications

Kronik

Shapira

1999

Surface Science Reports

1,529

804

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“…(2.26) is dominated by mobile, rather than static, charges. However, it may be very signi®cant in the depletion regime [35].…”

Section: Surface Space Charge Regionmentioning

confidence: 99%

Section: Super-bandgap Spvmentioning

confidence: 99%

Surface photovoltage phenomena: theory, experiment, and applications

Kronik

Shapira

1999

Surface Science Reports

1,529

804

View full text Add to dashboard Cite

“…When a semiconductor is illuminated, photoexcited minority carriers gather at the surface because of the built-in potential in the surface depletion region. The charge build-up forms an internal dipole that opposes the dipole stemming from the trap states and flattens the bands, assuming the surface states do not change significantly upon illumination , (see Figure b). Therefore, the surface photovoltage (SPV) raises the Fermi level closer to the vacuum level in an n-type semiconductor and lowers the work function, ϕ. Conversely, the SPV effect will increase the work function in a p-type semiconductor.…”

mentioning

confidence: 99%

Surface Photovoltage-Induced Ultralow Work Function Material for Thermionic Energy Converters

et al. 2019

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Low work function materials are essential for efficient thermionic energy converters (TECs), electronics, and electron emission devices. Much effort has been put into finding thermally stable material combinations that exhibit low work functions. Submonolayer coatings of alkali metals have proven to significantly reduce the work function; however, a work function less than 1 eV has not been reached. We report a record-low work function of 0.70 eV by inducing a surface photovoltage (SPV) in an n-type semiconductor with an alkali metal coating. Ultraviolet photoelectron spectroscopy indicates a work function of 1.06 eV for cesium/oxygen-activated GaAs consistent with density functional theory model predictions. By illuminating with a 532 nm laser we induce an additional shift down to 0.70 eV due to the SPV. Further, we apply the SPV to the collector of an experimental TEC and demonstrate an I – V curve shift consistent with the collector work function reduction. This method opens an avenue toward efficient TECs and next-generation electron emission devices.

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“…However, more generally the surface photovoltage is determined by photogenerated majority carriers, and this flattening potential (also represented as the photo-induced offset of the Fermi-level of majority carriers) is defined as a photovoltage. 1,2,[5][6][7] In this condition, V ph,OC =∆V F,OC The band gap of the silicon is taken to be 1.12 eV and the doping concentration is set at 2 × 10 17 cm −3 for both the n-type and p-type regions. 8,9 In a solid-state semiconductor p-n junction, differing doping levels gives rise to a builtin voltage (V bi ) between the n-type and p-type regions (as illustrated in Fig.…”

Section: Si Photovoltages In Solid-state Systemsmentioning

confidence: 99%

Utilizing Band Diagrams to Interpret the Photovoltage and Photocurrent in Photoanodes: A Semiclassical Device Modeling Study

2020

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Photoelectrochemcial (PEC) cells offer a promising route for supplying the world’s population with sufficient energy in an environmentally friendly manner. However, inefficiency remains a major bottleneck towards the large-scale commercialization of PEC cells. The photovoltage and photocurrent serve as important design metrics when assessing the efficiency of photoanodes within PEC cells. However, to date wide disagreement persists regarding how the photovoltage should be physically interpreted; this lack of consensus is further coupled to physical interpretations of the photocurrent. In this work, we utilize state-of-the-art device modeling to help clarify the physical origins of both the photovoltage and photocurrent in photoanodes. Through a systematic examination of a model photoanode (hematite), we correlate directly measurable current-voltage characteristics with operational band diagrams. It is shown that by directly mapping specific operating points of either equal current or equal voltage (both illuminated and in the dark) to band diagram plots, one is able to obtain substantial insights regarding the physical nature of both the photocurrent and photovoltage. By aiding the community wide effort to arrive at a consensus on these concepts, we aim to further enable the design of higher efficiency photoanodes.

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Analysis of the surface photovoltaic effect in photoconductors: CdS

Cited by 18 publications

References 18 publications

Surface photovoltage phenomena: theory, experiment, and applications

Surface photovoltage phenomena: theory, experiment, and applications

Surface Photovoltage-Induced Ultralow Work Function Material for Thermionic Energy Converters

Utilizing Band Diagrams to Interpret the Photovoltage and Photocurrent in Photoanodes: A Semiclassical Device Modeling Study

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