Single-crystalline germanium nanomembrane photodetectors on foreign nanocavities

Xia, Zhenyang; Song, Haomin; Kim, Munho; Zhou, Ming; Chang, Tzu‐Hsuan; Liu, Dong; Yin, Xin; Xiong, Kanglin; Mi, Hongyi; Wang, Xudong; Xia, Fengnian; Yu, Zongfu; Jack, Zhenqiang; Gan, Qiaoqiang

doi:10.1126/sciadv.1602783

Cited by 85 publications

(68 citation statements)

References 49 publications

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“…In particular, this mechanism has been employed to enhance the optical absorption of planar ultrathin photocatalytic α‐Fe 2 O 3 films for efficient water splitting . By controlling the planar cavity structure, we demonstrated that the optical absorption within 1.5‐nm‐thick Ge film and MoS 2 monolayers can be enhanced significantly, opening the door to high‐efficiency ultrathin‐film energy conversion materials, structures, and devices . Importantly, this principle is general and can be implemented into photocatalytic systems to boost the photoconversion efficiency.…”

Section: Introductionmentioning

confidence: 94%

Ultrathin‐Film Titania Photocatalyst on Nanocavity for CO₂ Reduction with Boosted Catalytic Efficiencies

Song

Liang

et al. 2018

Global Challenges

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Photocatalytic CO2 reduction with water to hydrocarbons represents a viable and sustainable process toward greenhouse gas reduction and fuel/chemical production. Development of more efficient catalysts is the key to mitigate the limits in photocatalytic processes. Here, a novel ultrathin‐film photocatalytic light absorber (UFPLA) with TiO2 films to design efficient photocatalytic CO2 conversion processes is created. The UFPLA structure conquers the intrinsic trade‐off between optical absorption and charge carrier extraction efficiency, that is, a solar absorber should be thick enough to absorb majority of the light allowable by its bandgap but thin enough to allow charge carrier extraction for reactions. The as‐obtained structures significantly improve TiO2 photocatalytic activity and selectivity to oxygenated hydrocarbons than the benchmark photocatalyst (Aeroxide P25). Remarkably, UFPLAs with 2‐nm‐thick TiO2 films result in hydrocarbon formation rates of 0.967 mmol g−1 h−1, corresponding to 1145 times higher activity than Aeroxide P25. This observation is confirmed by femtosecond transient absorption spectroscopic experiments where longer charge carrier lifetimes are recorded for the thinner films. The current work demonstrates a powerful strategy to control light absorption and catalysis in CO2 conversion and, therefore, creates new and transformative ways of converting solar energy and greenhouse gas to alcohol fuels/chemicals.

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Section: Introductionmentioning

confidence: 94%

Ultrathin‐Film Titania Photocatalyst on Nanocavity for CO₂ Reduction with Boosted Catalytic Efficiencies

Song

Liang

et al. 2018

Global Challenges

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“…In this case, the destructive interference only occurs in a narrow wavelength range and this can be used to obtain spectrally selective light absorption. A recent study demonstrated the realization of efficient and ultrathin MOS cavities based on single crystalline Ge for spectrally selective photodetector applications . This strong light‐matter interaction for an MOS design is specifically important for 2D semiconductors, such as TMDs.…”

Section: Light Trapping Schemesmentioning

confidence: 99%

“…This in turn induces an inherent limit in the performance of ultrathin amorphous based semiconductor designs. A recent study demonstrated a fabrication route for a sub‐10 nm single crystalline Ge layer for photodetection application . The authors claimed that this approach can also be adopted for other type of semiconductors.…”

Section: Light Trapping Schemesmentioning

confidence: 99%

Semiconductor Thin Film Based Metasurfaces and Metamaterials for Photovoltaic and Photoelectrochemical Water Splitting Applications

Ghobadi

Özbay

2019

Advanced Optical Materials

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throughput and large-scale compatibility. The photoactive material is generally composed of single or multiple semiconductor layers responsible for harvesting solar energy. This harvested solar irradiation can be used to generate electricity using photovoltaic (PV) devices, or it can be converted to chemical energy in the form of hydrogen which is the case for photoelectrochemical water splitting (PEC-WS). In both PV and PEC-WS applications, the ultimate goal is to establish an efficient photon capturing and electron collecting scheme to generate a huge number of photocarriers (including electron-hole pairs) with rational carrier dynamics (efficient charge generation, separation, and collection). This means that the device should be optically thick enough to generate high carrier's density and electrically thin enough to collect photogenerated carrier before they recombine. When light impinges a semiconductor surface, a part of the light is reflected back due to the mismatch between the air and the semiconductor layer refractive index. The rest will propagate within the bulk until it is fully absorbed by the semiconductor slab. The optical penetration depth (LPD) is defined as the depth at which the incident power falls to 1/e (≈37%) of its input value. This parameter differs from one semiconductor to another and it depends on the extinction coefficient (κ) of the In both photovoltaic (PV) and photoelectrochemical water splitting (PEC-WS) solar conversion devices, the ultimate aim is to design highly efficient, low cost, and large-scale compatible cells. To achieve this goal, the main step is the efficient coupling of light into active layer. This can be obtained in bulkysemiconductor-based designs where the active layer thickness is larger than light penetration depth. However, most low-bandgap semiconductors have a carrier diffusion length much smaller than the light penetration depth. Thus, photogenerated electron-hole pairs will recombine within the semiconductor bulk. Therefore, an efficient design should fully harvest light in dimensions in the order of the carriers' diffusion length to maximize their collection probability. For this aim, in recent years, many studies based on metasurfaces and metamaterials were conducted to obtain broadband and near-unity light absorption in subwavelength ultrathin semiconductor thicknesses. This review summarizes these strategies in five main categories: light trapping based on i) strong interference in planar multilayer cavities, ii) metal nanounits, iii) dielectric units, iv) designed semiconductor units, and v) trapping scaffolds. The review highlights recent studies in which an ultrathin active layer has been coupled to the above-mentioned trapping schemes to maximize the cell optical performance.

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“…For this purpose, a series connection of cavities with doubleresonance behavior was utilized. Moreover, a recent study presents a fabrication route that synthe sizes nanometerscalethick, singlecrys talline Ge coatings for spectrally selective photodetection [67]. Incorporating an ultrathin Ge layer on top of a prede signed MI cavity leads to the formation of a spectrally selective metal-insula tor-semiconductor (MIS)based photo detector, as depicted in Figure 3(a)-(c).…”

Section: Photovoltaics and Photodetectionmentioning

confidence: 99%

Strong Interference in Planar, Multilayer Perfect Absorbers: Achieving High-Operational Performances in Visible and Near-Infrared Regimes

Ghobadi

Hajian

Bütün

et al. 2019

IEEE Nanotechnology Mag.

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Single-crystalline germanium nanomembrane photodetectors on foreign nanocavities

Abstract: High-yield, high throughput method creates nanomembrane photodetectors with unique optoelectronic properties.

Cited by 85 publications

References 49 publications

Ultrathin‐Film Titania Photocatalyst on Nanocavity for CO₂ Reduction with Boosted Catalytic Efficiencies

Ultrathin‐Film Titania Photocatalyst on Nanocavity for CO₂ Reduction with Boosted Catalytic Efficiencies

Semiconductor Thin Film Based Metasurfaces and Metamaterials for Photovoltaic and Photoelectrochemical Water Splitting Applications

Strong Interference in Planar, Multilayer Perfect Absorbers: Achieving High-Operational Performances in Visible and Near-Infrared Regimes

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Single-crystalline germanium nanomembrane photodetectors on foreign nanocavities

Abstract: High-yield, high throughput method creates nanomembrane photodetectors with unique optoelectronic properties.

Cited by 85 publications

References 49 publications

Ultrathin‐Film Titania Photocatalyst on Nanocavity for CO2 Reduction with Boosted Catalytic Efficiencies

Ultrathin‐Film Titania Photocatalyst on Nanocavity for CO2 Reduction with Boosted Catalytic Efficiencies

Semiconductor Thin Film Based Metasurfaces and Metamaterials for Photovoltaic and Photoelectrochemical Water Splitting Applications

Strong Interference in Planar, Multilayer Perfect Absorbers: Achieving High-Operational Performances in Visible and Near-Infrared Regimes

Contact Info

Product

Resources

About

Ultrathin‐Film Titania Photocatalyst on Nanocavity for CO₂ Reduction with Boosted Catalytic Efficiencies

Ultrathin‐Film Titania Photocatalyst on Nanocavity for CO₂ Reduction with Boosted Catalytic Efficiencies