Nanomaterials

Research

8 pages, 1860 KiB

Open AccessCommunication

Conversion of Charge Carrier Polarity in MoTe₂ Field Effect Transistor via Laser Doping

by Hanul Kim, Inayat Uddin, Kenji Watanabe, Takashi Taniguchi, Dongmok Whang and Gil-Ho Kim

Nanomaterials 2023, 13(10), 1700; https://doi.org/10.3390/nano13101700 - 22 May 2023

Cited by 2 | Viewed by 1331

A two-dimensional (2D) atomic crystalline transition metal dichalcogenides has shown immense features, aiming for future nanoelectronic devices comparable to conventional silicon (Si). 2D molybdenum ditelluride (MoTe₂) has a small bandgap, appears close to that of Si, and is more favorable than [...] Read more.

A two-dimensional (2D) atomic crystalline transition metal dichalcogenides has shown immense features, aiming for future nanoelectronic devices comparable to conventional silicon (Si). 2D molybdenum ditelluride (MoTe₂) has a small bandgap, appears close to that of Si, and is more favorable than other typical 2D semiconductors. In this study, we demonstrate laser-induced p-type doping in a selective region of n-type semiconducting MoTe₂ field effect transistors (FET) with an advance in using the hexagonal boron nitride as passivation layer from protecting the structure phase change from laser doping. A single nanoflake MoTe₂-based FET, exhibiting initial n-type and converting to p-type in clear four-step doping, changing charge transport behavior in a selective surface region by laser doping. The device shows high electron mobility of about 23.4 cm²V⁻¹s⁻¹ in an intrinsic n-type channel and hole mobility of about 0.61 cm²V⁻¹s⁻¹ with a high on/off ratio. The device was measured in the range of temperature 77–300 K to observe the consistency of the MoTe₂-based FET in intrinsic and laser-dopped region. In addition, we measured the device as a complementary metal–oxide–semiconductor (CMOS) inverter by switching the charge-carrier polarity of the MoTe₂ FET. This fabrication process of selective laser doping can potentially be used for larger-scale MoTe₂ CMOS circuit applications. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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9 pages, 2068 KiB

Open AccessCommunication

Enhanced Diffractive Circular Dichroism from Stereoscopic Plasmonic Molecule Array

by Liangliang Gu, Rong Shu, Xiangfeng Liu, Haifeng Hu and Qiwen Zhan

Nanomaterials 2023, 13(7), 1175; https://doi.org/10.3390/nano13071175 - 25 Mar 2023

Cited by 1 | Viewed by 1282

Abstract

Artificial nanostructures with large optical chiral responses have been intensively investigated recently. In this work, we propose a diffractive circular dichroism enhancement technique using stereoscopic plasmonic molecule structures. According to the multipole expansion analysis, the z-component of the electric dipole becomes the dominant [...] Read more.

Artificial nanostructures with large optical chiral responses have been intensively investigated recently. In this work, we propose a diffractive circular dichroism enhancement technique using stereoscopic plasmonic molecule structures. According to the multipole expansion analysis, the z-component of the electric dipole becomes the dominant chiral scattering mechanism during the interaction between an individual plasmonic molecule and the plane wave at a grazing angle. For a periodical structure with the designed plasmonic molecule, large diffractive circular dichroism can be obtained, which can be associated with the Wood–Rayleigh anomaly. Such a diffractive circular dichroism enhancement is verified by the good agreement between numerical simulations and experimental results. The proposed approach can be potentially used to develop enhanced spectroscopy techniques to measure chiral information, which is very important for fundamental physical and chemical research and bio-sensing applications. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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10 pages, 2006 KiB

Open AccessArticle

Demonstration of a Learning-Empowered Fiber Specklegram Sensor Based on Focused Ion Beam Milling for Refractive Index Sensing

by Liangliang Gu, Han Gao and Haifeng Hu

Nanomaterials 2023, 13(4), 768; https://doi.org/10.3390/nano13040768 - 18 Feb 2023

Cited by 4 | Viewed by 1587

Abstract

We report a simple and robust fiber specklegram refractive index sensor with a multimode fiber-single mode fiber-multimode fiber structure based on focused ion beam milling. In this work, a series of fluid channels are etched on the single-mode fiber by using focused ion [...] Read more.

We report a simple and robust fiber specklegram refractive index sensor with a multimode fiber-single mode fiber-multimode fiber structure based on focused ion beam milling. In this work, a series of fluid channels are etched on the single-mode fiber by using focused ion beam milling to enhance the interaction between light and matter, and a deep learning model is employed to demodulate the sensing signal according to the speckle patterns collected from the output end of the multimode fiber. The feasibility and effectiveness of the proposed scheme were verified by rigorous experiments, and the test results showed that the demodulation accuracy and speed could reach 99.68% and 4.5 ms per frame, respectively, for the refractive index range of 1.3326 to 1.3679. The proposed sensing scheme has the advantages of low cost, easy implementation, and a simple measurement system, and it is expected to find applications in various chemical and biological sensing. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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12 pages, 3641 KiB

Open AccessArticle

Theoretical Optical Output Power Improvement of InGaN-Based Violet Laser Diode Using AlGaN/GaN Composite Last Quantum Barrier

by Zhenzhuo Zhang, Jing Yang, Degang Zhao, Feng Liang, Ping Chen and Zongshun Liu

Nanomaterials 2022, 12(22), 3990; https://doi.org/10.3390/nano12223990 - 12 Nov 2022

Cited by 6 | Viewed by 1604

Abstract

Electron leakage has an adverse influence on the optical output power for laser diodes (LDs), especially where the conventional last quantum barrier (LQB) in the multiple quantum well (MQW) active region may cause severe leakage problems. In this article, a composite last quantum [...] Read more.

Electron leakage has an adverse influence on the optical output power for laser diodes (LDs), especially where the conventional last quantum barrier (LQB) in the multiple quantum well (MQW) active region may cause severe leakage problems. In this article, a composite last quantum barrier (CLQB) composed of p-type doped AlGaN (p-AlGaN) and unintentionally doped GaN (u-GaN) layers is designed to replace the conventional one, for overcoming the problem of electron overflow. Theoretical calculations with LASTIP software demonstrate that CLQB with optimized parameters of Al composition, thickness and p-type doping concentration of the p-AlGaN layer in the CLQB can have a 50% improvement in slope efficiency (SE) compared with the conventional structure LD. This will help to realize a higher optical output power in InGaN-based violet LDs. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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9 pages, 2701 KiB

Open AccessEditor’s ChoiceArticle

Double Fano Resonance and Independent Regulation Characteristics in a Rectangular-like Nanotetramer Metasurface Structure

by Zhidong Zhang, Qingchao Zhang, Bo Li, Junbin Zang, Xiyuan Cao, Xiaolong Zhao and Chenyang Xue

Nanomaterials 2022, 12(19), 3479; https://doi.org/10.3390/nano12193479 - 5 Oct 2022

Cited by 3 | Viewed by 1339

Abstract

Fano resonance, which is based on a plasmonic metasurface, has many potential applications in various fields, such as biochemical sensors, slow light effect, and integrated optical circuits. In this study, a rectangular-like nanotetramer metasurface structure composed of four round-head nanorods was designed. The [...] Read more.

Fano resonance, which is based on a plasmonic metasurface, has many potential applications in various fields, such as biochemical sensors, slow light effect, and integrated optical circuits. In this study, a rectangular-like nanotetramer metasurface structure composed of four round-head nanorods was designed. The transmission spectrum, surface charge, and electrical field distributions of the proposed structure were simulated using the finite element method. A double Fano resonance profile was observed in the transmission spectrum. One of the Fano resonances was caused by the symmetry breaking and plasmon hybridization between the horizontal double rods, whereas the other resonance was due to the plasmonic modes’ hybridization among four nanorods. These resonances could be independently tuned because of different formation mechanisms. The number of Fano resonances could be adjusted by changing the coupling distance between the horizontal and vertical rods. The results contributed to designing the highly sensitive sensors based on the plasmonic metasurface. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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10 pages, 2666 KiB

Open AccessArticle

A Nanoscale Sensor Based on a Toroidal Cavity with a Built-In Elliptical Ring Structure for Temperature Sensing Application

by Feng Liu, Shubin Yan, Lifang Shen, Pengwei Liu, Lili Chen, Xiaoyu Zhang, Guang Liu, Jilai Liu, Tingsong Li and Yifeng Ren

Nanomaterials 2022, 12(19), 3396; https://doi.org/10.3390/nano12193396 - 28 Sep 2022

Cited by 7 | Viewed by 1369

Abstract

In this article, a refractive index sensor based on Fano resonance, which is generated by the coupling of a metal–insulator–metal (MIM) waveguide structure and a toroidal cavity with a built-in elliptical ring (TCER) structure, is presented. The finite element method (FEM) was employed [...] Read more.

In this article, a refractive index sensor based on Fano resonance, which is generated by the coupling of a metal–insulator–metal (MIM) waveguide structure and a toroidal cavity with a built-in elliptical ring (TCER) structure, is presented. The finite element method (FEM) was employed to analyze the propagation characteristics of the integral structure. The effects of refractive index and different geometric parameters of the structure on the sensing characteristics were evaluated. The maximum sensitivity was 2220 nm/RIU with a figure of merit (FOM) of 58.7, which is the best performance level that the designed structure could achieve. Moreover, due to its high sensitivity and simple structure, the refractive index sensor can be applied in the field of temperature detection, and its sensitivity is calculated to be 1.187 nm/℃. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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9 pages, 2904 KiB

Open AccessArticle

Fast-Response Photodetector Based on Hybrid Bi₂Te₃/PbS Colloidal Quantum Dots

by Lijing Yu, Pin Tian, Libin Tang, Qun Hao, Kar Seng Teng, Hefu Zhong, Biao Yue, Haipeng Wang and Shunying Yan

Nanomaterials 2022, 12(18), 3212; https://doi.org/10.3390/nano12183212 - 16 Sep 2022

Cited by 2 | Viewed by 1861

Abstract

Colloidal quantum dots (CQDs) as photodetector materials have attracted much attention in recent years due to their tunable energy bands, low cost, and solution processability. However, their intrinsically low carrier mobility and three-dimensional (3D) confinement of charges are unsuitable for use in fast-response [...] Read more.

Colloidal quantum dots (CQDs) as photodetector materials have attracted much attention in recent years due to their tunable energy bands, low cost, and solution processability. However, their intrinsically low carrier mobility and three-dimensional (3D) confinement of charges are unsuitable for use in fast-response and highly sensitive photodetectors, hence greatly restricting their application in many fields. Currently, 3D topological insulators, such as bismuth telluride (Bi₂Te₃), have been employed in high-speed broadband photodetectors due to their narrow bulk bandgap, high carrier mobility, and strong light absorption. In this work, the advantages of topological insulators and CQDs were realized by developing a hybrid Bi₂Te₃/PbS CQDs photodetector that exhibited a maximum responsivity and detectivity of 18 A/W and 2.1 × 10¹¹ Jones, respectively, with a rise time of 128 μs at 660 nm light illumination. The results indicate that such a photodetector has potential application in the field of fast-response and large-scale integrated optoelectronic devices. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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10 pages, 3351 KiB

Open AccessArticle

Importance of Structural Relaxation on the Electrical Characteristics and Bias Stability of Solution-Processed ZnSnO Thin-Film Transistors

by Yu-Jin Hwang, Do-Kyung Kim, Sang-Hwa Jeon, Ziyuan Wang, Jaehoon Park, Sin-Hyung Lee, Jaewon Jang, In Man Kang and Jin-Hyuk Bae

Nanomaterials 2022, 12(18), 3097; https://doi.org/10.3390/nano12183097 - 7 Sep 2022

Cited by 3 | Viewed by 1688

Abstract

Effect of structural relaxation (SR) on the electrical characteristics and bias stability of solution-processed zinc–tin oxide (ZTO) thin-film transistors (TFTs) were systematically investigated by controlling the annealing time of the ZTO semiconductor films. Note that SR was found to increase with increased annealing [...] Read more.

Effect of structural relaxation (SR) on the electrical characteristics and bias stability of solution-processed zinc–tin oxide (ZTO) thin-film transistors (TFTs) were systematically investigated by controlling the annealing time of the ZTO semiconductor films. Note that SR was found to increase with increased annealing time. Due to the increased SR, the ratio of oxygen vacancies (V_O) increased from 21.5% to 38.2%. According to increased V_O, the mobility in the saturation region was exhibited by a sixfold increase from 0.38 to 2.41 cm² V⁻¹ s⁻¹. In addition, we found that the threshold voltage negatively shifted from 3.08 to −0.95 V. Regarding the issue of bias stability, according to increased SR, positive-bias stress of the ZTO TFTs was enhanced, compared with reverse features of negative-bias stress. Our understanding is expected to provide a basic way to improve the electrical characteristics and bias stability of rare-metal-free oxide semiconductor TFTs, which have not been sufficiently studied. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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9 pages, 3748 KiB

Open AccessArticle

Quasi-Distributed Temperature and Strain Sensors Based on Series-Integrated Fiber Bragg Gratings

by Huajian Zhong, Xueya Liu, Cailing Fu, Baijie Xu, Jun He, Pengfei Li, Yanjie Meng, Chao Du, Lin Chen, Jian Tang and Yiping Wang

Nanomaterials 2022, 12(9), 1540; https://doi.org/10.3390/nano12091540 - 2 May 2022

Cited by 5 | Viewed by 1937

Abstract

Two types of series-integrated fiber Bragg gratings (SI-FBGs), i.e., strong and weak SI-FBGs, were inscribed in a standard single-mode fiber (SMF) using the femtosecond laser point-by-point technology. In the SI-FBGs inscribing system, the grating pitch of each FBG and the distance between the [...] Read more.

Two types of series-integrated fiber Bragg gratings (SI-FBGs), i.e., strong and weak SI-FBGs, were inscribed in a standard single-mode fiber (SMF) using the femtosecond laser point-by-point technology. In the SI-FBGs inscribing system, the grating pitch of each FBG and the distance between the two adjacent FBGs in the SI-FBGs can be flexibly controlled by adjusting the inscription parameters. The strong SI-FBGs with different grating pitches and the weak SI-FBGs with an identical grating pitch were employed to successfully measure the temperature distribution in a tube furnace and the strain distribution on a cantilever beam, respectively. A high spatial resolution of less than 1 mm was achieved during the distributed temperature sensing experiment. Moreover, the spatial resolution could be improved by decreasing the distance between the two adjacent FBGs, i.e., decreasing the FBG length and the space between the two adjacent FBGs. Hence, the inscribed high-quality SI-FBGs have great potential to be developed as various quasi-distributed sensors with a high spatial resolution. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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9 pages, 11107 KiB

Open AccessArticle

Topological Refraction in Kagome Split-Ring Photonic Insulators

by Huichang Li, Chen Luo, Tailin Zhang, Jianwei Xu, Xiang Zhou, Yun Shen and Xiaohua Deng

Nanomaterials 2022, 12(9), 1493; https://doi.org/10.3390/nano12091493 - 28 Apr 2022

Cited by 3 | Viewed by 2150

Abstract

A valley-Hall-like photonic insulator based on

C_{3 v}

Kagome split-ring is proposed. Theoretical analysis and numerical calculations illustrate that

C_{3 v}

symmetry can be broken not only by global rotation

α

but also individual rotation

θ

of the split rings, providing [...] Read more.

A valley-Hall-like photonic insulator based on

C_{3 v}

Kagome split-ring is proposed. Theoretical analysis and numerical calculations illustrate that

C_{3 v}

symmetry can be broken not only by global rotation

α

but also individual rotation

θ

of the split rings, providing topological phase transitions. Furthermore, refraction of the edge state from the interface into the background space at Zigzag termination is explored. It is shown that positive/negative refraction of the outgoing beam depends on the type of valley (K or

K^{'}

), from which the edge state is projected. These results provide a new way to manipulate terahertz wave propagation and facilitate the potential applications in directional collimation, beam splitting, negative refraction image, etc. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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13 pages, 3745 KiB

Open AccessArticle

Promoted Mid-Infrared Photodetection of PbSe Film by Iodine Sensitization Based on Chemical Bath Deposition

by Silu Peng, Haojie Li, Chaoyi Zhang, Jiayue Han, Xingchao Zhang, Hongxi Zhou, Xianchao Liu and Jun Wang

Nanomaterials 2022, 12(9), 1391; https://doi.org/10.3390/nano12091391 - 19 Apr 2022

Cited by 6 | Viewed by 2165

Abstract

In recent years, lead selenide (PbSe) has gained considerable attention for its potential applications in optoelectronic devices. However, there are still some challenges in realizing mid-infrared detection applications with single PbSe film at room temperature. In this paper, we use a chemical bath [...] Read more.

In recent years, lead selenide (PbSe) has gained considerable attention for its potential applications in optoelectronic devices. However, there are still some challenges in realizing mid-infrared detection applications with single PbSe film at room temperature. In this paper, we use a chemical bath deposition method to deposit PbSe thin films by varying deposition time. The effects of the deposition time on the structure, morphology, and optical absorption of the deposited PbSe films were investigated by x-ray diffraction, scanning electron microscopy, and infrared spectrometer. In addition, in order to activate the mid-infrared detection capability of PbSe, we explored its application in infrared photodetection by improving its crystalline quality and photoconductivity and reducing tge noise and high dark current of PbSe thin films through subsequent iodine treatment. The iodine sensitization PbSe film showed superior photoelectric properties compared to the untreated sample, which exhibited the maximum of responsiveness, which is 30.27 A/W at 808 nm, and activated its detection ability in the mid-infrared (5000 nm) by introducing PbI₂, increasing the barrier height of the crystallite boundary and carrier lifetimes. This facile synthesis strategy and the sensitization treatment process provide a potential experimental scheme for the simple, rapid, low-cost, and efficient fabrication of large-area infrared PbSe devices. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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10 pages, 13523 KiB

Open AccessArticle

Theoretical Analysis of Terahertz Frequency Multiplier Based on Semiconductor Superlattices

by Wei Feng, Shuting Wei, Yonghui Zheng, Chang Wang and Juncheng Cao

Nanomaterials 2022, 12(7), 1114; https://doi.org/10.3390/nano12071114 - 28 Mar 2022

Cited by 3 | Viewed by 1832

Abstract

We propose a terahertz frequency multiplier based on high order harmonic generation in a GaAs-based miniband superlattice driven by an electric field. The performance of the frequency multiplier is analyzed using the balance equation approach, which incorporates momentum and energy relaxation processes at [...] Read more.

We propose a terahertz frequency multiplier based on high order harmonic generation in a GaAs-based miniband superlattice driven by an electric field. The performance of the frequency multiplier is analyzed using the balance equation approach, which incorporates momentum and energy relaxation processes at different lattice temperatures. It is found that the generated high-order harmonic power is sensitive to temperature changes. The peak power appears around resonance between driving terahertz frequency and intrinsic Bloch frequency. In the presence of the magnetic field, the peak power shifts towards a stronger static electric field region. The simulated results about the dependence of the second and third harmonic powers on a DC electric field are in qualitative consistence with the experiments. The proposed terahertz frequency multiplier based on semiconductor superlattice, being compact and efficient, is provided as a good candidate for terahertz wave generation. Full article

(This article belongs to the Special Issue Advanced Semiconductor Nanomaterials for Electronic and Optoelectronic Applications)

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