Sustained electron tunneling at unbiased metal-insulator-semiconductor triboelectric contacts

Liu, Jun; Miao, Mengmeng; Jiang, Keren; Khan, Faheem; Goswami, Ankur; McGee, Ryan; Li, Zhi; Nguyễn, Loan; Hu, Zhiyu; Lee, Jungchul; Cadien, Ken; Thundat, Thomas

doi:10.1016/j.nanoen.2018.03.068

Cited by 114 publications

(151 citation statements)

References 29 publications

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“…[ 5 ] Recently, it was found that the CE will be very different when the semiconductor is involved. [ 6 ] The current can be generated by the contact or sliding of a P‐type semiconductor against an N‐type semiconductor [ 7–9 ] (or semiconductor against metal [ 10–12 ] ), and a novel electric generator was proposed. [ 7 ] This new type of electric generator is gaining attention for that a direct current can be generated without a rectifier module.…”

Section: Figurementioning

confidence: 99%

Scanning Probing of the Tribovoltaic Effect at the Sliding Interface of Two Semiconductors

et al. 2020

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can be generated by the contact or sliding of a P-type semiconductor against an N-type semiconductor [7][8][9] (or semiconductor against metal [10][11][12] ), and a novel electric generator was proposed. [7] This new type of electric generator is gaining attention for that a direct current can be generated without a rectifier module. [8][9][10][11] However, the mechanism of the current generation in the CE involving semiconductors is still under debate.For the contact between a P-type semiconductor and an N-type semiconductor, the PN junction will be formed at the interface. [13,14] It is highly suspected that the built-in electric field in the PN junction makes the CE between the semiconductors different from that between conventional materials. Considering that, Wang et al. pointed out that the generation of the continuous direct current induced by the sliding of P-type semiconductor against N-type semiconductor is similar to the photovoltaic effect, and can be referred to as the "tribovoltaic effect." [15] The only difference is that the electron-hole pairs in tribovoltaic effect are excited during friction, in which the energy is released due to either the transition of electrons from the surface states of one side to that of another side in the contact or sliding, [16][17][18][19][20][21] or the energy released while forming a new bond at the interface, [22] just as it occurs in the CE between two conventional materials. [23][24][25][26] Then, the electron-hole pairs are separated by the built-in electric field and the external current flowing from the P-side to the N-side will be induced, as it occurs in the photovoltaic effect. [27][28][29] According to the tribovoltaic effect, the excitation efficiency of electron-hole pairs highly depends on the density of surface states of the semiconductors and the bonding interactions. Hence, the tribovoltaic current may be related to the density of surface states of the semiconductors and the sliding load, which can significantly affect the bonding interactions at the sliding interface. [22] In this work, the direct current is generated by sliding an N-type semiconductor tip over a Si sample surface using conductive atomic force microscopy (CAFM). [30,31] Both P-type and N-type Si samples with various doping concentrations are used in the experiments. Further, the Si samples are treated by inductively coupled plasma reactive ion etching (ICP-RIE), which can significantly increase the density of surface states of the semiconductors by doping or introducing defects on the surface. [32,33] It is revealed that the current density in the sliding experiments increases with increasing of the density of surface Contact electrification (CE or triboelectrification) is a common phenomenon, which can occur for almost all types of materials. In previous studies, the CE between insulators and metals has been widely discussed, while CE involving semiconductors is only recently. Here, a tribo-current is generated by sliding an N-type diamond coated tip on a P-type or N-type Si wafer...

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Section: Figurementioning

confidence: 99%

Scanning Probing of the Tribovoltaic Effect at the Sliding Interface of Two Semiconductors

et al. 2020

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“…[5,6] It is suggested that the decreased Φ B in a metal/semicondcuting polymer junction under compression may facilitate the electron transfer for DC generation. Accordingly, it is found that the Φ B is decreased from 0.7 to 0.62 eV under sliding condition, which is possibly due to the decreased interfacial atomic distance as will be revealed by the MD simulation result or the surface band bending induced by the localized triboelectric electric field E (as high as 10 8 V m −1 ).…”

Section: Doi: 101002/aelm201900464mentioning

confidence: 99%

“…[8] In DFT studies, intensified charge redistribution is also observed at decreased atomic distance, which is adopted to explain the enhanced electrostatic charge transfer in polymerbased TENGs. To evaluate the quality of the generator system, fill factor (FF) is adopted, which compares the maximum power P m to the theoretical power: [5,6] www.advelectronicmat.de effort should be dedicated to increasing the shunt resistance (R sh ), as well as decreasing the series resistance (R s ) and diode loss. Figure 3a shows the I and V output as a function of external resistance R. It can be seen that the V increases and the I decreases as predicted by Equations (S6) and (S7), Supporting Information.…”

Section: Doi: 101002/aelm201900464mentioning

confidence: 99%

“…[1] The performance of TENGs is optimal only at high frequency due to the dielectric displacement current mechanism, while the environmental mechanical sources usually have frequencies lower than 10 Hz. [3,[5][6][7][8][9][10] The tribo-tunneling transport tip-enhanced current generation, as reported by Liu et al [3,6] using conductive-atomic force microscope (C-AFM), show that the tribo-tunneling current density ( J) output can be boosted by the nano-sized contact (tip radius R ≈ 30 nm) up to 10 6 A m −2 due to the enhanced electronic excitation and strong localized electric field E. It has been reported that a micro-tip (tip radius R ≈ 30 µm) sliding system produces a current density of 35 A m −2 while larger tip radius (R ≈ 100-300 µm) yields a current density of 10 A m −2 in the test probe sliding system. [3,[5][6][7][8][9][10] The tribo-tunneling transport tip-enhanced current generation, as reported by Liu et al [3,6] using conductive-atomic force microscope (C-AFM), show that the tribo-tunneling current density ( J) output can be boosted by the nano-sized contact (tip radius R ≈ 30 nm) up to 10 6 A m −2 due to the enhanced electronic excitation and strong localized electric field E. It has been reported that a micro-tip (tip radius R ≈ 30 µm) sliding system produces a current density of 35 A m −2 while larger tip radius (R ≈ 100-300 µm) yields a current density of 10 A m −2 in the test probe sliding system.…”

mentioning

confidence: 99%

“…[4] In contrast, the non-equilibrium tribo-tunneling phenomenon, recently discovered in the semiconductor-based Schottky moving contacts, is capable of generating a continuous DC current as high as 100 A m −2 regardless of the motion direction, and not limited by the mechanical source frequency. [5,6] However, scaling up the concept with micro-electromechanical systems (MEMS)-fabricated tip array is time-consuming and costly. [5,6] However, scaling up the concept with micro-electromechanical systems (MEMS)-fabricated tip array is time-consuming and costly.…”

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confidence: 99%

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Tribo‐Tunneling DC Generator with Carbon Aerogel/Silicon Multi‐Nanocontacts

Cheikh

Bao

et al. 2019

Adv Elect Materials

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Mechanical energy conversion technologies such as piezoelectric or triboelectric nanogenerators are able to harvest environmental energy (e.g., vibration, wind, tidal wave) and human body motion for powering electric vehicles, sensor networks, and wearable devices. [1][2][3] Traditional triboelectric nanogenerators (TENGs) may generate high voltage but with extremely low AC current ( J ≈ 0.01-0.1 A m −2 ) density. [1] The performance of TENGs is optimal only at high frequency due to the dielectric displacement current mechanism, while the environmental mechanical sources usually have frequencies lower than 10 Hz. [4] In contrast, the non-equilibrium tribo-tunneling phenomenon, recently discovered in the semiconductor-based Schottky moving contacts, is capable of generating a continuous DC current as high as 100 A m −2 regardless of the motion direction, and not limited by the mechanical source frequency. [3,[5][6][7][8][9][10] The tribo-tunneling transport tip-enhanced current generation, as reported by Liu et al. [3,6] using conductive-atomic force microscope (C-AFM), show that the tribo-tunneling current density ( J) output can be boosted by the nano-sized contact (tip radius R ≈ 30 nm) up to 10 6 A m −2 due to the enhanced electronic excitation and strong localized electric field E. It has been reported that a micro-tip (tip radius R ≈ 30 µm) sliding system produces a current density of 35 A m −2 while larger tip radius (R ≈ 100-300 µm) yields a current density of 10 A m −2 in the test probe sliding system. [5,6] However, scaling up the concept with micro-electromechanical systems (MEMS)-fabricated tip array is time-consuming and costly. The metal micro-tips also cause substrate surface scratching, which impacts the sustainability of the power generation. Moreover, the relatively low open-circuit voltage (V oc , 300-600 mV) of the single metal/Si sliding unit is insufficient for practical applications in electronics. To address those issues, we developed a carbon aerogel-based system in this work, which scales up the DC output and enhances the Voc output by one order via naturally formed Schottky nanocontacts.Carbon aerogel is electrically conductive, synthetic ultralight material composed of 3D network structures of interconnected amorphous carbon nanoparticles. [11] It has been widely used for nanocomposite, electrodes, desalination filters, and heterogeneous catalysis due to its large surface area. [12] In this work, Although tip-enhanced tribo-tunneling in metal/semiconductor point nanocontact is capable of producing DC with high current density, scaling up the process for power harvesting for practical applications is challenging due to the complexity of tip array fabrication and insufficient voltage output. Here, it is demonstrated that mechanical contact between a carbon aerogel and silicon (SiO 2 /Si) interface naturally forms multiple nanocontacts for tribo-tunneling current generation with an open-circuit voltage output (V OC ) reaching 2 V, and short-circuit DC current output (I SC ) of ≈15 µA. It h...

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High‐Performance Flexible Schottky DC Generator via Metal/Conducting Polymer Sliding Contacts

Yang

Benner

Guo

et al. 2021

Adv Funct Materials

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Dynamic Schottky direct‐current (DC) generators hold great promise for ambient mechanical energy harvesting as it overcomes the low‐current output limitation in conventional approaches. However, the lack of a fundamental understanding of DC generation in conducting polymer‐based Schottky generators has hindered their application for self‐powered wearable and implantable electronics. Here, a high‐performance, flexible Schottky DC generator with metal/conducting polymer sliding contact system is demonstrated, which exhibits a large current density (J) up to 20 A m–2 for single contact geometry and a scaled‐up DC output reaching 200 µA (J = 0.73 A m–2) and 0.8 V. The design of flexibility in such a Schottky DC generator is inherited from the long‐chain polymer concept, leading to the demonstration of a variety of device configuration of free‐standing thin film, supported thin film and nanocomposite prototype toward practical applications. It is revealed that the sliding junctions may exhibit a different mechanical energy conversion mechanism compared to the compressive conducting polymer Schottky junctions. It is also proven that the magnitude and polarity of DC generation is determined by the Schottky contact formation and interfacial electric field. The concept of a flexible Schottky generator not only shows great promise for next‐generation, self‐powered wearable devices, but also provides potential mechanisms for developing novel wearable sensors.

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Sustained electron tunneling at unbiased metal-insulator-semiconductor triboelectric contacts

Cited by 114 publications

References 29 publications

Scanning Probing of the Tribovoltaic Effect at the Sliding Interface of Two Semiconductors

Scanning Probing of the Tribovoltaic Effect at the Sliding Interface of Two Semiconductors

Tribo‐Tunneling DC Generator with Carbon Aerogel/Silicon Multi‐Nanocontacts

High‐Performance Flexible Schottky DC Generator via Metal/Conducting Polymer Sliding Contacts

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