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Dithieno[3',2':3,4;2'',3'':5,6]benzo[1,2-c][1,2,5]oxadiazole-based polymer donors with deep HOMO levels 173
Xiongfeng Li, Jingui Xu, Zuo Xiao, Xingzhu Wang, Bin Zhang, Liming Ding
2021, 42(6): 060501. doi: 10.1088/1674-4926/42/6/060501

A review of β-Ga2O3 single crystal defects, their effects on device performance and their formation mechanism 158
Bo Fu, Zhitai Jia, Wenxiang Mu, Yanru Yin, Jian Zhang, Xutang Tao
2019, 40(1): 011804. doi: 10.1088/1674-4926/40/1/011804

As a wide-bandgap semiconductor (WBG), β-Ga2O3 is expected to be applied to power electronics and solar blind UV photodetectors. In this review, defects in β-Ga2O3 single crystals were summarized, including dislocations, voids, twin, and small defects. Their effects on device performance were discussed. Dislocations and their surrounding regions can act as paths for the leakage current of SBD in single crystals. However, not all voids lead to leakage current. There’s no strong evidence yet to show small defects affect the electrical properties. Doping impurity was definitely irrelated to the leakage current. Finally, the formation mechanism of the defects was analyzed. Most small defects were induced by mechanical damages. The screw dislocation originated from a subgrain boundary. The edge dislocation lying on a plane slightly tilted towards the (102) plane, the (101) being the possible slip plane. The voids defects like hollow nanopipes, PNPs, NSGs and line-shaped grooves may be caused by the condensation of excess oxygen vacancies, penetration of tiny bubbles or local meltback. The nucleation of twin lamellae occurred at the initial stage of " shoulder part” during the crystal growth. These results are helpful in controlling the occurrence of crystal defects and improving the device performance.

Multiple SiGe/Si layers epitaxy and SiGe selective etching for vertically stacked DRAM 132
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.

Progress and trends of low-jitter fractional-N PLL 109
Jun Yin, Haoran Li, Xiaoqi Lin, Rui P. Martins, Pui-In Mak
2025, 46(7): 070203. doi: 10.1088/1674-4926/25040035

Two-dimensional silicon nanomaterials for optoelectronics 100
Xuebiao Deng, Huai Chen, Zhenyu Yang
2023, 44(4): 041101. doi: 10.1088/1674-4926/44/4/041101

Silicon nanomaterials have been of immense interest in the last few decades due to their remarkable optoelectronic responses, elemental abundance, and higher biocompatibility. Two-dimensional silicon is one of the new allotropes of silicon and has many compelling properties such as quantum-confined photoluminescence, high charge carrier mobilities, anisotropic electronic and magnetic response, and non-linear optical properties. This review summarizes the recent advances in the synthesis of two-dimensional silicon nanomaterials with a range of structures (silicene, silicane, and multilayered silicon), surface ligand engineering, and corresponding optoelectronic applications.

Wearable sweat biosensors on textiles for health monitoring 93
Yuqing Shi, Ziyu Zhang, Qiyao Huang, Yuanjing Lin, Zijian Zheng
2023, 44(2): 021601. doi: 10.1088/1674-4926/44/2/021601

With the rapid technological innovation in materials engineering and device integration, a wide variety of textile-based wearable biosensors have emerged as promising platforms for personalized healthcare, exercise monitoring, and pre-diagnostics. This paper reviews the recent progress in sweat biosensors and sensing systems integrated into textiles for wearable body status monitoring. The mechanisms of biosensors that are commonly adopted for biomarkers analysis are first introduced. The classification, fabrication methods, and applications of textile conductors in different configurations and dimensions are then summarized. Afterward, innovative strategies to achieve efficient sweat collection with textile-based sensing patches are presented, followed by an in-depth discussion on nanoengineering and system integration approaches for the enhancement of sensing performance. Finally, the challenges of textile-based sweat sensing devices associated with the device reusability, washability, stability, and fabrication reproducibility are discussed from the perspective of their practical applications in wearable healthcare.

A review of ToF-based LiDAR 83
Jie Ma, Shenglong Zhuo, Lei Qiu, Yuzhu Gao, Yifan Wu, Ming Zhong, Rui Bai, Miao Sun, Patrick Yin Chiang
2024, 45(10): 101201. doi: 10.1088/1674-4926/24040015

In recent years, propelled by the rapid iterative advancements in digital imaging technology and the semiconductor industry, encompassing microelectronic design, manufacturing, packaging, and testing, time-of-flight (ToF)-based imaging systems for acquiring depth information have garnered considerable attention from both academia and industry. This technology has emerged as a focal point of research within the realm of 3D imaging. Owing to its relatively straightforward principles and exceptional performance, ToF technology finds extensive applications across various domains including human−computer interaction, autonomous driving, industrial inspection, medical and healthcare, augmented reality, smart homes, and 3D reconstruction, among others. Notably, the increasing maturity of ToF-based LiDAR systems is evident in current developments. This paper comprehensively reviews the fundamental principles of ToF technology and LiDAR systems, alongside recent research advancements. It elucidates the innovative aspects and technical challenges encountered in both transmitter (TX) and receiver (RX), providing detailed discussions on corresponding solutions. Furthermore, the paper explores prospective avenues for future research, offering valuable insights for subsequent investigations.

A wide-bandgap copolymer donor with a 5-methyl-4H-dithieno[3,2-e:2',3'-g]isoindole-4,6(5H)-dione unit 81
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

Review of the SiC LDMOS power device 76
Ziwei Hu, Jiafei Yao, Ang Li, Qi Sun, Man Li, Kemeng Yang, Jun Zhang, Jing Chen, Maolin Zhang, Yufeng Guo
2024, 45(8): 081501. doi: 10.1088/1674-4926/24010029

Silicon carbide (SiC), as a third-generation semiconductor material, possesses exceptional material properties that significantly enhance the performance of power devices. The SiC lateral double-diffused metal–oxide–semiconductor (LDMOS) power devices have undergone continuous optimization, resulting in an increase in breakdown voltage (BV) and ultra-low specific on-resistance (Ron,sp). This paper has summarized the structural optimizations and experimental progress of SiC LDMOS power devices, including the trench-gate technology, reduced surface field (RESURF) technology, doping technology, junction termination techniques and so on. The paper is aimed at enhancing the understanding of the operational mechanisms and providing guidelines for the further development of SiC LDMOS power devices.

Indium–gallium–zinc–oxide thin-film transistors: Materials, devices, and applications 74
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.