This work reports important fundamental advancements in multiwall carbon nanotube (MWCNT) rectenna devices by creating and optimizing new diode structures to allow optical rectification with air‐stable devices. The incorporation of double‐insulator layer tunnel diodes, fabricated for the first time on MWCNT arrays, enables the use of air‐stable top metals (Al and Ag) with excellent asymmetry for rectification applications. Asymmetry is increased by as much as 10 times, demonstrating the effectiveness of incorporating multiple dielectric layers to control electron tunneling in MWCNT diode structures. MWCNT tip opening also reduces device resistance up to 75% due to an increase in diode contact area to MWCNT inner walls. This effect is consistent for different oxide materials and thicknesses. A number of insulator layers, including Al2O3, HfO2, TiO2, ZnO, and ZrO2, in both single‐ and then double‐insulator configurations are tested. Resistance increases exponentially with insulator thickness and decreases with electron affinity. These results are used to characterize double‐insulator diode performance. Finally, for the most asymmetric device structure, Al2O3‐HfO2(4/4 nm), optical rectification at a frequency of 470 THz (638 nm) is demonstrated. These results open the door for designing efficient MWCNT rectenna devices with more material flexibility, including air‐stable, transparent, and conductive top electrode materials.
Numerous efforts have been undertaken to develop rectifying antennas operating at high frequencies, especially dedicated to light harvesting and photodetection applications. However, the development of efficient high frequency rectifying antennas has been a major technological challenge both due to a lack of comprehension of the underlying physics and limitations in the fabrication techniques. Various rectification strategies have been implemented, including metal‐insulator‐metal traveling‐wave diodes, plasmonic nanogap optical antennas, and whisker diodes, although all show limited high‐frequency operation and modest conversion efficiencies. Here a new type of rectifying antenna based on plasmonic carrier generation is demonstrated. The proposed structure consists of a resonant metallic conical nano‐antenna tip in contact with the oxide surface of an oxide/metal bilayer. The conical shape allows for an improved current generation based on plasmon‐mediated electromagnetic‐to‐electron conversion, an effect exploiting the nanoscale‐tip contact of the rectifying antenna, and proportional to the antenna resonance and to the surface‐electron scattering. Importantly, this solution provides rectification operation at 280 THz (1064 nm) with a 100‐fold increase in efficiency compared to previously reported results. Finally, the conical rectifying antenna is also demonstrated to operate at 384 THz (780 nm), hence paving a way toward efficient rectennas toward the visible range.
more » « less- NSF-PAR ID:
- 10446892
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Energy Materials
- Volume:
- 12
- Issue:
- 15
- ISSN:
- 1614-6832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The discovery of oxide electronics is of increasing importance today as one of the most promising new technologies and manufacturing processes for a variety of electronic and optoelectronic applications such as next-generation displays, batteries, solar cells, and photodetectors. The high potential use seen in oxide electronics is due primarily to their high carrier mobilities and their ability to be fabricated at low temperatures. However, since the majority of oxide semiconductors are n-type oxides, current applications are limited to unipolar devices, eventually developing oxide-based bipolar devices such as p-n diodes and complementary metal-oxide semiconductors. We have contributed to wide range of oxide semiconductors and their electronics and optoelectronic device applications. Particularly, we have demonstrated n-type oxide-based thin film transistors (TFT), integrating In2O3-based n-type oxide semiconductors from binary cation materials to ternary cation species including InZnO, InGaZnO (IGZO), and InAlZnO. We have suggested channel/metallization contact strategies to achieve stable TFT performance, identified vacancy-based native defect doping mechanisms, suggested interfacial buffer layers to promote charge injection capability, and established the role of third cation species on the carrier generation and carrier transport. More recently, we have reported facile manufacturing of p-type SnOx through reactive magnetron sputtering from a Sn metal target. The fabricated p-SnOx was found to be devoid of metallic phase of Sn from x-ray photoelectron spectroscopy and demonstrated stable performance in a fully oxide based p-n heterojunction together with n-InGaZnO. The oxide-based p-n junctions exhibited a high rectification ratio greater than 103 at ±3 V, a low saturation current of ~2x10-10, and a small turn-on voltage of -0.5 V. With all the previous achievements and investigations about p-type oxide semiconductors, challenges remain for implementing p-type oxide realization. For the implementation of oxide-based p-n heterojunctions, the performance needs to be further enhanced. The current on/off ration may be limited, in our device structure, due to either high reverse saturation current (or current density) or non-ideal performance. In this study, two rational strategies are suggested to introduce an “intrinsic” layer, which is expected to reduce the reverse saturation current between p-SnOx and n-IGZO and hence increase the on/off ratio. The carrier density of n-IGZO is engineered in-situ during the sputtering process, by which compositionally homogeneous IGZO with significantly reduced carrier density is formed at the interface. Then, higher carrier density IGZO is formed continuously on the lower carrier density IGZO during the sputtering process without any exposure of the sample to the air. Alternatively, heterogeneous oxides of MgO and SiO2 are integrated into between p-SnOx and n-IGZO, by which the defects on the surface can be passivated. The interfacial properties are thoroughly investigated using transmission electron microscopy and atomic force microscopy. The I-V characteristics are compared between the set of devices integrated with two types of “intrinsic” layers. The current research results are expected to contribute to the development of p-type oxides and their industrial application manufacturing process that meets current processing requirements, such as mass production in p-type oxide semiconductors.more » « less
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The discovery of oxide electronics is of increasing importance today as one of the most promising new technologies and manufacturing processes for a variety of electronic and optoelectronic applications such as next-generation displays, batteries, solar cells, memory devices, and photodetectors[1]. The high potential use seen in oxide electronics is due primarily to their high carrier mobilities and their ability to be fabricated at low temperatures[2]. However, since the majority of oxide semiconductors are n-type oxides, current applications are limited to unipolar devices, eventually developing oxide-based bipolar devices such as p-n diodes and complementary metal-oxide semiconductors. We have contributed to a wide range of oxide semiconductors and their electronics and optoelectronic device applications. Particularly, we have demonstrated n-type oxide-based thin film transistors (TFT), integrating In 2 O 3 -based n-type oxide semiconductors from binary cation materials to ternary cation species including InZnO, InGaZnO (IGZO), and InAlZnO. We have suggested channel/metallization contact strategies to achieve stable and high TFT performance[3, 4], identified vacancy-based native defect doping mechanisms[5], suggested interfacial buffer layers to promote charge injection capability[6], and established the role of third cation species on the carrier generation and carrier transport[7]. More recently, we have reported facile manufacturing of p-type SnOx through reactive magnetron sputtering from a Sn metal target[8]. The fabricated p-SnOx was found to be devoid of metallic phase of Sn from x-ray photoelectron spectroscopy and demonstrated stable performance in a fully oxide-based p-n heterojunction together with n-InGaZnO. The oxide-based p-n junctions exhibited a high rectification ratio greater than 10 3 at ±3 V, a low saturation current of ~2x10 -10 , and a small turn-on voltage of -0.5 V. In this presentation, we review recent achievements and still remaining issues in transition metal oxide semiconductors and their device applications, in particular, bipolar applications including p-n heterostructures and complementary metal-oxide-semiconductor devices as well as single polarity devices such as TFTs and memristors. In addition, the fundamental mechanisms of carrier transport behaviors and doping mechanisms that govern the performance of these oxide-based devices will also be discussed. ACKNOWLEDGMENT This work was supported by the U.S. National Science Foundation (NSF) Award No. ECCS-1931088. S.L. and H.W.S. acknowledge the support from the Improvement of Measurement Standards and Technology for Mechanical Metrology (Grant No. 20011028) by KRISS. K.N. was supported by Basic Science Research Program (NRF-2021R11A1A01051246) through the NRF Korea funded by the Ministry of Education. REFERENCES [1] K. Nomura et al. , Nature, vol. 432, no. 7016, pp. 488-492, Nov 25 2004. [2] D. C. Paine et al. , Thin Solid Films, vol. 516, no. 17, pp. 5894-5898, Jul 1 2008. [3] S. Lee et al. , Journal of Applied Physics, vol. 109, no. 6, p. 063702, Mar 15 2011, Art. no. 063702. [4] S. Lee et al. , Applied Physics Letters, vol. 104, no. 25, p. 252103, 2014. [5] S. Lee et al. , Applied Physics Letters, vol. 102, no. 5, p. 052101, Feb 4 2013, Art. no. 052101. [6] M. Liu et al. , ACS Applied Electronic Materials, vol. 3, no. 6, pp. 2703-2711, 2021/06/22 2021. [7] A. Reed et al. , Journal of Materials Chemistry C, 10.1039/D0TC02655G vol. 8, no. 39, pp. 13798-13810, 2020. [8] D. H. Lee et al. , ACS Applied Materials & Interfaces, vol. 13, no. 46, pp. 55676-55686, 2021/11/24 2021.more » « less
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Abstract Enhanced electromagnetic fields within plasmonic nanocavity mode volumes enable multiple significant effects that lead to applications in both the linear and nonlinear optical regimes. In this work, enhanced second‐harmonic generation (SHG) is demonstrated from individual plasmonic nanopatch antennas (NPAs) which are formed by separating silver nanocubes from a smooth gold film using a sub‐10 nm zinc oxide spacer layer. When the NPAs are excited at their fundamental plasmon frequency, a 104‐fold increase in the intensity of the SHG wave is observed. Moreover, by integrating quantum emitters that have an absorption energy at the fundamental frequency, a second‐order nonlinear exciton–polariton strong coupling response is observed with a Rabi splitting energy of 19 meV. The nonlinear frequency conversion using NPAs thus provides an excellent platform for nonlinear control of the light−matter interactions in both weak and strong coupling regimes which will have a great potential for applications in optical engineering and information processing.
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Abstract 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 (SiO2/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 has a theoretical current density (J *) on the order of 100 A m−2. Molecular dynamics simulation and atomistic field theory show that a strong localized electronic excitation can be induced at a dynamic carbon/SiO2sliding interface, which is in good agreement with the experimental results. The DC power output is enhanced by the intense local pressure at the presence of nanocontacts, as well as the increased sliding velocityv . To demonstrate the method for practical applications, light‐emitting diodes (LEDs) with different colors are successfully lighted by a single‐carbon aerogel monolith/SiO2sliding unit, and the DC electricity is stored in a capacitor without an additional rectification circuit.
