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A wide-bandgap copolymer donor with a 5-methyl-4H-dithieno[3,2-e:2',3'-g]isoindole-4,6(5H)-dione unit 144
Anxin Sun, Jingui Xu, Guanhua Zong, Zuo Xiao, Yong Hua, Bin Zhang, Liming Ding
2021, 42(10): 100502. doi: 10.1088/1674-4926/42/10/100502

Multiple SiGe/Si layers epitaxy and SiGe selective etching for vertically stacked DRAM 127
Zhenzhen Kong, Hongxiao Lin, Hailing Wang, Yanpeng Song, Junjie Li, Xiaomeng Liu, Anyan Du, Yuanhao Miao, Yiwen Zhang, Yuhui Ren, Chen Li, Jiahan Yu, Jinbiao Liu, Jingxiong Liu, Qinzhu Zhang, Jianfeng Gao, Huihui Li, Xiangsheng Wang, Junfeng Li, Henry H. Radamson, Chao Zhao, Tianchun Ye, Guilei Wang
2023, 44(12): 124101. doi: 10.1088/1674-4926/44/12/124101

Fifteen periods of Si/Si0.7Ge0.3 multilayers (MLs) with various SiGe thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition (RPCVD). Several methods were utilized to characterize and analyze the ML structures. The high resolution transmission electron microscopy (HRTEM) results show that the ML structure with 20 nm Si0.7Ge0.3 features the best crystal quality and no defects are observed. Stacked Si0.7Ge0.3 ML structures etched by three different methods were carried out and compared, and the results show that they have different selectivities and morphologies. In this work, the fabrication process influences on Si/SiGe MLs are studied and there are no significant effects on the Si layers, which are the channels in lateral gate all around field effect transistor (L-GAAFET) devices. For vertically-stacked dynamic random access memory (VS-DRAM), it is necessary to consider the dislocation caused by strain accumulation and stress release after the number of stacked layers exceeds the critical thickness. These results pave the way for the manufacture of high-performance multivertical-stacked Si nanowires, nanosheet L-GAAFETs, and DRAM devices.

Indium–gallium–zinc–oxide thin-film transistors: Materials, devices, and applications 105
Ying Zhu, Yongli He, Shanshan Jiang, Li Zhu, Chunsheng Chen, Qing Wan
2021, 42(3): 031101. doi: 10.1088/1674-4926/42/3/031101

Since the invention of amorphous indium–gallium–zinc–oxide (IGZO) based thin-film transistors (TFTs) by Hideo Hosono in 2004, investigations on the topic of IGZO TFTs have been rapidly expanded thanks to their high electrical performance, large-area uniformity, and low processing temperature. This article reviews the recent progress and major trends in the field of IGZO-based TFTs. After a brief introduction of the history of IGZO and the main advantages of IGZO-based TFTs, an overview of IGZO materials and IGZO-based TFTs is given. In this part, IGZO material electron travelling orbitals and deposition methods are introduced, and the specific device structures and electrical performance are also presented. Afterwards, the recent advances of IGZO-based TFT applications are summarized, including flat panel display drivers, novel sensors, and emerging neuromorphic systems. In particular, the realization of flexible electronic systems is discussed. The last part of this review consists of the conclusions and gives an outlook over the field with a prediction for the future.

High-speed electro-absorption modulated laser 96
Zhenyao Li, Chen Lyu, Xuliang Zhou, Mengqi Wang, Haotian Qiu, Yejin Zhang, Hongyan Yu, Jiaoqing Pan
2025, 46(11): 111401. doi: 10.1088/1674-4926/25030015

Currently, the global 5G network, cloud computing, and data center industries are experiencing rapid development. The continuous growth of data center traffic has driven the vigorous progress in high-speed optical transceivers for optical interconnection within data centers. The electro-absorption modulated laser (EML), which is widely used in optical fiber communications, data centers, and high-speed data transmission systems, represents a high-performance photoelectric conversion device. Compared to traditional directly modulated lasers (DMLs), EMLs demonstrate lower frequency chirp and higher modulation bandwidth, enabling support for higher data rates and longer transmission distances. This article introduces the composition, working principles, manufacturing processes, and applications of EMLs. It reviews the progress on advanced indium phosphide (InP)-based EML devices from research institutions worldwide, while summarizing and comparing data transmission rates and key technical approaches across various studies.

A review on SRAM-based computing in-memory: Circuits, functions, and applications 95
Zhiting Lin, Zhongzhen Tong, Jin Zhang, Fangming Wang, Tian Xu, Yue Zhao, Xiulong Wu, Chunyu Peng, Wenjuan Lu, Qiang Zhao, Junning Chen
2022, 43(3): 031401. doi: 10.1088/1674-4926/43/3/031401

Artificial intelligence (AI) processes data-centric applications with minimal effort. However, it poses new challenges to system design in terms of computational speed and energy efficiency. The traditional von Neumann architecture cannot meet the requirements of heavily data-centric applications due to the separation of computation and storage. The emergence of computing in-memory (CIM) is significant in circumventing the von Neumann bottleneck. A commercialized memory architecture, static random-access memory (SRAM), is fast and robust, consumes less power, and is compatible with state-of-the-art technology. This study investigates the research progress of SRAM-based CIM technology in three levels: circuit, function, and application. It also outlines the problems, challenges, and prospects of SRAM-based CIM macros.

Design space of electrostatic chuck in etching chamber 95
Yuchun Sun, Jia Cheng, Yijia Lu, Yuemin Hou, Linhong Ji
2015, 36(8): 084004. doi: 10.1088/1674-4926/36/8/084004

One of the core semiconductor devices is the electrostatic chuck. It has been widely used in plasma-based and vacuum-based semiconductor processing. The electrostatic chuck plays an important role in adsorbing and cooling/heating wafers, and has technical advantages on non-edge exclusion, high reliability, wafer planarity, particles reduction and so on. This article extracts key design elements from the existing knowledge and techniques of electrostatic chuck by the method proposed by Paul and Beitz, and establishes a design space systematically. The design space is composed of working objects, working principles and working structures. The working objects involve electrostatic chuck components and materials, classifications, and relevant properties; the working principles involve clamping force, residual force, and temperature control; the working structures describe how to compose an electrostatic chuck and to fulfill the overall functions. The systematic design space exhibits the main issues during electrostatic chuck design. The design space will facilitate and inspire designers to improve the design quality and shorten the design time in the conceptual design.

A review of silicon-based wafer bonding processes, an approach to realize the monolithic integration of Si-CMOS and III–V-on-Si wafers 94
Shuyu Bao, Yue Wang, Khaw Lina, Li Zhang, Bing Wang, Wardhana Aji Sasangka, Kenneth Eng Kian Lee, Soo Jin Chua, Jurgen Michel, Eugene Fitzgerald, Chuan Seng Tan, Kwang Hong Lee
2021, 42(2): 023106. doi: 10.1088/1674-4926/42/2/023106

The heterogeneous integration of III–V devices with Si-CMOS on a common Si platform has shown great promise in the new generations of electrical and optical systems for novel applications, such as HEMT or LED with integrated control circuitry. For heterogeneous integration, direct wafer bonding (DWB) techniques can overcome the materials and thermal mismatch issues by directly bonding dissimilar materials systems and device structures together. In addition, DWB can perform at wafer-level, which eases the requirements for integration alignment and increases the scalability for volume production. In this paper, a brief review of the different bonding technologies is discussed. After that, three main DWB techniques of single-, double- and multi-bonding are presented with the demonstrations of various heterogeneous integration applications. Meanwhile, the integration challenges, such as micro-defects, surface roughness and bonding yield are discussed in detail.

Review on three-dimensional graphene: synthesis and joint photoelectric regulation in photodetectors 91
Bingkun Wang, Jinqiu Zhang, Huijuan Wu, Fanghao Zhu, Shanshui Lian, Genqiang Cao, Hui Ma, Xurui Hu, Li Zheng, Gang Wang
2025, 46(7): 071401. doi: 10.1088/1674-4926/25010015

Graphene has garnered significant attention in photodetection due to its exceptional optical, electrical, mechanical, and thermal properties. However, the practical application of two-dimensional (2D) graphene in optoelectronic fields is limited by its weak light absorption (only 2.3%) and zero bandgap characteristics. Increasing light absorption is a critical scientific challenge for developing high-performance graphene-based photodetectors. Three-dimensional (3D) graphene comprises vertically grown stacked 2D-graphene layers and features a distinctive porous structure. Unlike 2D-graphene, 3D-graphene offers a larger specific surface area, improved electrochemical activity, and high chemical stability, making it a promising material for optoelectronic detection. Importantly, 3D-graphene has an optical microcavity structure that enhances light absorption through interaction with incoming light. This paper systematically reviews and analyzes the current research status and challenges of 3D-graphene-based photodetectors, aiming to explore feasible development paths for these devices and promote their industrial application.

A 0.5–3.0 GHz SP4T RF switch with improved body self-biasing technique in 130-nm SOI CMOS 89
Hao Zhang, Qiangsheng Cui, Xu Yan, Jiahui Shi, Fujiang Lin
2020, 41(10): 102404. doi: 10.1088/1674-4926/41/10/102404

A single-pole four-throw (SP4T) RF switch with charge-pump-based controller is designed and implemented in a commercial 130-nm silicon-on-insulator (SOI) CMOS process. An improved body self-biasing technique based on diodes is utilized to simplify the controlling circuitry and improve the linearity. A multistack field-effect-transistor (FET) structure with body floating technique is employed to provide good power-handling capability. The proposed design demonstrates a measured input 0.1-dB compression point of 38.5 dBm at 1.9 GHz, an insertion loss of 0.27 dB/0.33 dB and an isolation of 35 dB/27 dB at 900 MHz/1.9 GHz, respectively. The overall chip area is only 0.49 mm2. This RF switch can be used in GSM/WCDMA/LTE front-end modules.

Contact planarization and passivation lift tungsten diselenide PMOS performance 84
Haoyu Peng, Ping-Heng Tan, Jiangbin Wu
2025, 46(11): 110401. doi: 10.1088/1674-4926/25080028