Editorial

3 pages, 168 KiB

Open AccessEditorial

Editorial for the Special Issue “Microsystem for Electronic Devices”

by Xinrui Ding

Micromachines 2023, 14(4), 720; https://doi.org/10.3390/mi14040720 - 24 Mar 2023

Viewed by 726

The field of microsystems is a rapidly evolving area with a wide range of applications in the field of electronics [...] Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

Research

Jump to: Editorial

12 pages, 3246 KiB

Open AccessArticle

Modeling and Simulations of 4H-SiC/6H-SiC/4H-SiC Single Quantum-Well Light Emitting Diode Using Diffusion Bonding Technique

by Muhammad Haroon Rashid, Ants Koel, Toomas Rang, Nadeem Nasir, Haris Mehmood and Salman Cheema

Micromachines 2021, 12(12), 1499; https://doi.org/10.3390/mi12121499 - 30 Nov 2021

Cited by 4 | Viewed by 2303

Abstract

In the last decade, silicon carbide (SiC) has emerged as a potential material for high-frequency electronics and optoelectronics applications that may require elevated temperature processing. SiC exists in more than 200 different crystallographic forms, referred to as polytypes. Based on their remarkable physical [...] Read more.

In the last decade, silicon carbide (SiC) has emerged as a potential material for high-frequency electronics and optoelectronics applications that may require elevated temperature processing. SiC exists in more than 200 different crystallographic forms, referred to as polytypes. Based on their remarkable physical and electrical characteristics, such as better thermal and electrical conductivities, 3C-SiC, 4H-SiC, and 6H-SiC are considered as the most distinguished polytypes of SiC. In this article, physical device simulation of a light-emitting diode (LED) based on the unique structural configuration of 4H-SiC and 6H-SiC layers has been performed which corresponds to a novel material joining technique, called diffusion welding/bonding. The proposed single quantum well (SQW) edge-emitting SiC-based LED has been simulated using a commercially available semiconductor device simulator, SILVACO TCAD. Moreover, by varying different design parameters, the current-voltage characteristics, luminous power, and power spectral density have been calculated. Our proposed LED device exhibited promising results in terms of luminous power efficiency and external quantum efficiency (EQE). The device numerically achieved a luminous efficiency of 25% and EQE of 16.43%, which is at par performance for a SQW LED. The resultant LED structure can be customized by choosing appropriate materials of varying bandgaps to extract the light emission spectrum in the desired wavelength range. It is anticipated that the physical fabrication of our proposed LED by direct bonding of SiC-SiC wafers will pave the way for the future development of efficient and cost-effective SiC-based LEDs. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

11 pages, 5725 KiB

Open AccessArticle

Nanoscale-Precision Removal of Copper in Integrated Circuits Based on a Hybrid Process of Plasma Oxidation and Femtosecond Laser Ablation

by Shuai Wang, Yaoyu Wang, Shizhuo Zhang, Lingfeng Wang, Shuai Chen, Huai Zheng, Chen Zhang, Sheng Liu, Gary J. Cheng and Feng Liu

Micromachines 2021, 12(10), 1188; https://doi.org/10.3390/mi12101188 - 30 Sep 2021

Cited by 4 | Viewed by 2121

Abstract

Copper (Cu) is the main interconnect conductor for integrated circuits (IC), and its processing quality is very important to device performance. Herein, a hybrid process of plasma oxidation and femtosecond laser (fs-laser) ablation was proposed for the nanoscale precision removal of Cu in [...] Read more.

Copper (Cu) is the main interconnect conductor for integrated circuits (IC), and its processing quality is very important to device performance. Herein, a hybrid process of plasma oxidation and femtosecond laser (fs-laser) ablation was proposed for the nanoscale precision removal of Cu in integrated circuits. In this hybrid process, the surface layer of Cu was oxidized to the copper oxide by plasma oxidation, and then the fs-laser with a laser fluence lower than the Cu ablation threshold was used to remove the copper oxide without damaging the underlying Cu. Theoretically, the surface temperature evolutions of Cu and copper oxide under the femtosecond laser were studied by the two-temperature model, and it was revealed that the ablation threshold of copper oxide is much lower than that of Cu. The experimental results showed that the ablation threshold of copper oxide is lower than that of Cu, which is consistent with the theoretical analysis. Using the hybrid process, a surface roughness of 3 nm and a removal accuracy of 4 nm were obtained in the process of Cu film processing, which were better than those obtained by fs-laser ablation. This demonstrated that the hybrid process has good application potential in the field of copper micromachining. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Graphical abstract

12 pages, 4777 KiB

Open AccessArticle

A Luminous Efficiency-Enhanced Laser Lighting Device with a Micro-Angle Tunable Filter to Recycle Unconverted Blue Laser Rays

by Xinrui Ding, Ruixiang Qian, Liang Xu, Zongtao Li, Jiasheng Li, Caiman Yan and Binhai Yu

Micromachines 2021, 12(10), 1144; https://doi.org/10.3390/mi12101144 - 23 Sep 2021

Cited by 1 | Viewed by 1828

Abstract

In this work, a phosphor converter with small thickness and low concentration, based on a micro-angle tunable tilted filter (ATFPC), was proposed for hybrid-type laser lighting devices to solve the problem of silicone phosphor converters’ carbonizing under high-energy density. Taking advantage of the [...] Read more.

In this work, a phosphor converter with small thickness and low concentration, based on a micro-angle tunable tilted filter (ATFPC), was proposed for hybrid-type laser lighting devices to solve the problem of silicone phosphor converters’ carbonizing under high-energy density. Taking advantage of the filter and the scattering characteristics of microphosphors, two luminous areas are generated on the converter. Compared with conventional phosphor converters (CPCs), the lighting effects of ATFPCs are adjustable using tilt angles. When the tilt angle of the micro filter is 20°, the luminous flux of the ATPFCs is increased by 11.5% at the same concentration; the maximum temperature (MT) of ATFPCs is reduced by 22.8% under the same luminous flux and the same correlated color temperature (CCT) 6500 K. This new type of lighting device provides an alternative way to improve the luminous flux and heat dissipation of laser lighting. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Graphical abstract

10 pages, 2227 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Micro-Prism Patterned Remote Phosphor Film for Enhanced Luminous Efficiency and Color Uniformity of Phosphor-Converted Light-Emitting Diodes

by Jiadong Yu, Shudong Yu, Ting Fu and Yong Tang

Micromachines 2021, 12(9), 1117; https://doi.org/10.3390/mi12091117 - 17 Sep 2021

Cited by 3 | Viewed by 2302

Abstract

In this work, we propose micro-prism patterned remote phosphor (RP) films to enhance both luminous efficiency and color uniformity (CU) of remote phosphor-converted light-emitting diodes (rpc-LEDs) simultaneously. On the incident surface of the RP film, one micro-prism film is used to extract backward [...] Read more.

In this work, we propose micro-prism patterned remote phosphor (RP) films to enhance both luminous efficiency and color uniformity (CU) of remote phosphor-converted light-emitting diodes (rpc-LEDs) simultaneously. On the incident surface of the RP film, one micro-prism film is used to extract backward light by double reflection. On the exit surface, the other micro-prism film is adopted to retain blue light inside the RP film, thus enhancing the phosphor excitation. Experimental results show that double prism-patterned RP (DP-RP) film configuration shows a luminous flux of 55.16 lm, which is 45.1% higher than that of RP film configuration at 300 mA. As regards the CU, the DP-RP film configuration reduces the angular CIE-x and CIE-y standard variations by 68% and 69.32%, respectively, compared with the pristine device. Moreover, the DP-RP film configuration shows excellent color stability under varying driving currents. Since micro-prism films can be easily fabricated by a roll-to-roll process, the micro-prism patterned RP film can be an alternative to a conventional RP layer to enable the practical application of rpc-LEDs. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

10 pages, 3152 KiB

Open AccessArticle

Improving the External Quantum Efficiency of High-Power GaN-Based Flip-Chip LEDs by Using Sidewall Composite Reflective Micro Structure

by Liang Xu, Kaiping Fan, Huiqing Sun and Zhiyou Guo

Micromachines 2021, 12(9), 1073; https://doi.org/10.3390/mi12091073 - 04 Sep 2021

Cited by 3 | Viewed by 2871

Abstract

For high-power applications, it is important to improve the light extraction efficiency and light output of the vertical direction of LEDs. Flip-chip LEDs (FCLEDs) with an Ag/SiO₂/distributed Bragg reflector/SiO₂ composite reflection micro structure (CRS) were fabricated. Compared with the normal [...] Read more.

For high-power applications, it is important to improve the light extraction efficiency and light output of the vertical direction of LEDs. Flip-chip LEDs (FCLEDs) with an Ag/SiO₂/distributed Bragg reflector/SiO₂ composite reflection micro structure (CRS) were fabricated. Compared with the normal Ag-based FCLEDs, the light output power of the CRS-FCLEDs was increased by 6.3% at an operational current of 1500 mA, with the corresponding external quantum efficiency improved by 6.0%. Further investigation proved that the CRS structure exhibited higher reflectance compared with the commonly used Ag-mirror reflective structure, which originates from the increased reflective area in the sidewall and partial area of the n-GaN contact orifices. It exhibited markedly smaller optical degradation and thus higher device reliability as compared to normal Ag-based FCLED. Moreover, the light emission intensity distributions and far-field angular light emission measurements show that the CRS-FCLED has a strengthened light output in the vertical direction, which shows great potential for applications in high-power fields, such as headlamps for automobiles. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

12 pages, 4651 KiB

Open AccessArticle

Pool Boiling Performance of Multilayer Micromeshes for Commercial High-Power Cooling

by Kairui Tang, Jingjing Bai, Siyu Chen, Shiwei Zhang, Jie Li, Yalong Sun and Gong Chen

Micromachines 2021, 12(8), 980; https://doi.org/10.3390/mi12080980 - 18 Aug 2021

Cited by 7 | Viewed by 2863

Abstract

With the rapid development of electronics, thermal management has become one of the most crucial issues. Intense research has focused on surface modifications used to enhance heat transfer. In this study, multilayer copper micromeshes (MCMs) are developed for commercial compact electronic cooling. Boiling [...] Read more.

With the rapid development of electronics, thermal management has become one of the most crucial issues. Intense research has focused on surface modifications used to enhance heat transfer. In this study, multilayer copper micromeshes (MCMs) are developed for commercial compact electronic cooling. Boiling heat transfer performance, including critical heat flux (CHF), heat transfer coefficients (HTCs), and the onset of nucleate boiling (ONB), are investigated. The effect of micromesh layers on the boiling performance is studied, and the bubbling characteristics are analyzed. In the study, MCM-5 shows the highest critical heat flux (CHF) of 207.5 W/cm² and an HTC of 16.5 W(cm²·K) because of its abundant micropores serving as nucleate sites, and outstanding capillary wicking capability. In addition, MCMs are compared with other surface structures in the literature and perform with high competitiveness and potential in commercial applications for high-power cooling. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

10 pages, 3076 KiB

Open AccessArticle

Improving the Performance of Micro-Textured Cutting Tools in Dry Milling of Ti-6Al-4V Alloys

by Ze Wu, Youqiang Xing and Jiansong Chen

Micromachines 2021, 12(8), 945; https://doi.org/10.3390/mi12080945 - 11 Aug 2021

Cited by 6 | Viewed by 1761

Abstract

Micro-textured tools were fabricated by making textures on rake faces and filling them with molybdenum disulfide. Dry milling of Ti-6Al-4V alloys was carried out with the micro-textured tools and conventional tools for comparison. Results showed that micro-textured tools can reduce the resultant cutting [...] Read more.

Micro-textured tools were fabricated by making textures on rake faces and filling them with molybdenum disulfide. Dry milling of Ti-6Al-4V alloys was carried out with the micro-textured tools and conventional tools for comparison. Results showed that micro-textured tools can reduce the resultant cutting forces, cutting temperatures, and power consumption by approximately 15%, 10%, and 5%, respectively. Meanwhile, the developed tools can improve tool lives by approximately 20–25%. The radial width of cut, the cutting speed, and the axial depth of cut all had statistical and physical effects on the energy consumption per unit of volume in dry milling of Ti-6Al-4V alloys, while the feed per tooth seemed to have no significant effect. The mechanism for improved performance of micro-textured tools can be mainly interpreted as their self-lubricating function. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

14 pages, 4380 KiB

Open AccessArticle

Numerical and Experimental Investigations of Micro Thermal Performance in a Tube with Delta Winglet Pairs

by Jiangbo Wang, Ting Fu, Liangcai Zeng, Guang Chen and Fue-sang Lien

Micromachines 2021, 12(7), 786; https://doi.org/10.3390/mi12070786 - 30 Jun 2021

Cited by 3 | Viewed by 1698

Abstract

In this research, a novel vortex generator (VG) is presented. The experimental and numerical investigations were carried out to study the micro thermal-hydraulic performance in a heated tube. The numerical results showed that the fluid in the core flow region and the near-wall [...] Read more.

In this research, a novel vortex generator (VG) is presented. The experimental and numerical investigations were carried out to study the micro thermal-hydraulic performance in a heated tube. The numerical results showed that the fluid in the core flow region and the near-wall region was fully mixed because of the longitudinal vortices created by the vortex generators. In addition, the experimental results showed that the heat transfer coefficient (

h

) decreased with the increasing pitch ratio (

P R

) value, while the friction coefficient exhibited the opposite trend. With the increasing ration angle (

R A

) numbers, the

h

values decreased while the

f

numbers increased. In addition, the maximum and minimum values of the fraction ratio were 1.66 and 4.27, while these values of the Nusselt number ratio were 1.24 and 1.83. The maximum thermal enhancement factor (TEF) was 1.21 when

P R

= 0.5,

R A

= 0° and

R e

= 9090. The heat transfer enhancement mechanism of the vortex generator is explained from the microscopic point of view. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

17 pages, 7559 KiB

Open AccessArticle

An Electrostatic Self-Excited Resonator with Pre-Tension/Pre-Compression Constraint for Active Rotation Control

by Ruide Yun, Yangsheng Zhu, Zhiwei Liu, Jianmei Huang, Xiaojun Yan and Mingjing Qi

Micromachines 2021, 12(6), 650; https://doi.org/10.3390/mi12060650 - 01 Jun 2021

Cited by 2 | Viewed by 2241

Abstract

We report a novel electrostatic self-excited resonator driven by DC voltage that achieves variable velocity-position characteristics via applying the pre-tension/pre-compression constraint. The resonator consists of a simply supported micro-beam, two plate electrodes, and two adjustable constraint bases, and it can be under pre-compression [...] Read more.

We report a novel electrostatic self-excited resonator driven by DC voltage that achieves variable velocity-position characteristics via applying the pre-tension/pre-compression constraint. The resonator consists of a simply supported micro-beam, two plate electrodes, and two adjustable constraint bases, and it can be under pre-compression or pre-tension constraint by adjusting the distance L between two constraint bases (when beam length l > L, the resonator is under pre-compression and when l < L, it is under pre-tension). The oscillating velocity of the beam reaches the maximum value in the position around electrodes under the pre-compression constraint and reaches the maximum value in the middle position between two electrodes under the pre-tension condition. By changing the constraint of the microbeam, the position of the maximum velocity output of the oscillating beam can be controlled. The electrostatic self-excited resonator with a simple constraint structure under DC voltage has great potential in the field of propulsion of micro-robots, such as active rotation control of flapping wings. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

13 pages, 10540 KiB

Open AccessArticle

Effect of Solution and Aging Temperatures on Microstructure and Mechanical Properties of 10Cr13Co13Mo5Ni3W1VE(S280) Steel

by Jinyan Zhong, Zun Chen, Shanglin Yang, Songmei Li, Jianhua Liu and Mei Yu

Micromachines 2021, 12(5), 566; https://doi.org/10.3390/mi12050566 - 17 May 2021

Cited by 6 | Viewed by 1886

Abstract

The article investigated the effects of solution and ging temperatures on microstructure and mechanical properties of ultra-high strength stainless steel 10Cr13Co13Mo5Ni3W1VE(S280). Higher solution temperatures can improve impact toughness because of the quantity reduction of submicron-sized particles which act as microporous nucleation sites. S280 [...] Read more.

The article investigated the effects of solution and ging temperatures on microstructure and mechanical properties of ultra-high strength stainless steel 10Cr13Co13Mo5Ni3W1VE(S280). Higher solution temperatures can improve impact toughness because of the quantity reduction of submicron-sized particles which act as microporous nucleation sites. S280 has the best mechanical properties at 1080 °C solution temperature. After quenching, the steel is completely martensite with almost no retained austenite. Aging at 560 °C results in peak strength due to the precipitation of fine carbides coherent zones. The loss of precipitates/matrix coherency and precipitates coarsening cause a decrease in strength at higher aging temperatures. Good strength and toughness obtained at 540 °C aging temperature are attributed to fine and dispersed strengthening phases such as Cr₂C and Fe₂Mo, and the recovery of austenite in high-density dislocation martensite matrix. The details of electron microscopy research, strengthening and toughening mechanisms are discussed. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

9 pages, 4459 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Color-Tunable White LEDs with Single Chip Realized through Phosphor Pattern and Thermal-Modulating Optical Film

by Zhenpeng Su, Bo Zhao, Zheng Gong, Yang Peng, Fan Bai, Huai Zheng and Sang Woo Joo

Micromachines 2021, 12(4), 421; https://doi.org/10.3390/mi12040421 - 12 Apr 2021

Cited by 4 | Viewed by 2176

Abstract

In this paper, a new method to regulate the correlated color temperature (CCT) of white light-emitting diodes (LEDs) is proposed for the single-chip packaging structure, in which the blue light distribution emitted from the chip in the red/yellow phosphor layer was modulated through [...] Read more.

In this paper, a new method to regulate the correlated color temperature (CCT) of white light-emitting diodes (LEDs) is proposed for the single-chip packaging structure, in which the blue light distribution emitted from the chip in the red/yellow phosphor layer was modulated through changing the paraffin-polydimethylsiloxane (PDMS) film transparence and haze. The results show that the transmittance of the paraffin-PDMS film can be modulated from 49.76% to 97.64%, while the haze of that ranges from 88.19% to 63.10%. When the thickness of paraffin-PDMS film is 0.6 mm, and the paraffin-PDMS film concentration is 30 wt%, the CCT of white LED decreases from 15177 K to 3615 K with the increase of thermal load in the paraffin-PDMS film. The modulating range of its CCT reaches 11562 K. The maximum CCT variation at the same test condition is only 536 K in the repeated experiments within one week. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

12 pages, 3526 KiB

Open AccessArticle

Effect of Surface Microstructure on the Heat Dissipation Performance of Heat Sinks Used in Electronic Devices

by Yuxin You, Beibei Zhang, Sulian Tao, Zihui Liang, Biao Tang, Rui Zhou and Dong Yuan

Micromachines 2021, 12(3), 265; https://doi.org/10.3390/mi12030265 - 04 Mar 2021

Cited by 15 | Viewed by 2780

Abstract

Heat sinks are widely used in electronic devices with high heat flux. The design and build of microstructures on heat sinks has shown effectiveness in improving heat dissipation efficiency. In this paper, four kinds of treatment methods were used to make different microstructures [...] Read more.

Heat sinks are widely used in electronic devices with high heat flux. The design and build of microstructures on heat sinks has shown effectiveness in improving heat dissipation efficiency. In this paper, four kinds of treatment methods were used to make different microstructures on heat sink surfaces, and thermal radiation coating also applied onto the heat sink surfaces to improve thermal radiation. The surface roughness, thermal emissivity and heat dissipation performance with and without thermal radiation coating of the heat sinks were studied. The result shows that with an increase of surface roughness, the thermal emissivity can increase up to 2.5 times. With thermal radiation coating on a surface with microstructures, the heat dissipation was further improved because the heat conduction at the coating and heat sink interface was enhanced. Therefore, surface treatment can improve the heat dissipation performance of the heat sink significantly by enhancing the thermal convection, radiation and conduction. Full article

(This article belongs to the Special Issue Microsystem for Electronic Devices)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Microsystem for Electronic Devices

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (13 papers)

Editorial

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI