Two-dimensional (2D) anisotropic materials, such as B-P, B-As, GeSe, GeAs, ReSe2, KP15 and their hybrid systems, exhibit unique crystal structures and extraordinary anisotropy. This review presents a comprehensive comparison of various 2D anisotropic crystals as well as relevant FETs and photodetectors, especially on their particular anisotropy in optical and electrical properties. First, the structure of typical 2D anisotropic crystal as well as the analysis of structural anisotropy is provided. Then, recent researches on anisotropic Raman spectra are reviewed. Particularly, a brief measurement principle of Raman spectra under three typical polarized measurement configurations is introduced. Finally, recent progress on the electrical and photoelectrical properties of FETs and polarization-sensitive photodetectors based on 2D anisotropic materials is summarized for the comparison between different 2D anisotropic materials. Beyond the high response speed, sensitivity and on/off ratio, these 2D anisotropic crystals exhibit highly conduction ratio and dichroic ratio which can be applied in terms of polarization sensors, polarization spectroscopy imaging, optical radar and remote sensing.
J. Semicond. 2019, 40 (6): 061001Ziqi Zhou, Yu Cui, Ping-Heng Tan, Xuelu Liu, Zhongming Wei. Optical and electrical properties of two-dimensional anisotropic materials[J]. Journal of Semiconductors, 2019, 40(6): 061001. doi: 10.1088/1674-4926/40/6/061001.
Z Q Zhou, Y Cui, P H Tan, X L Liu, Z M Wei, Optical and electrical properties of two-dimensional anisotropic materials[J]. J. Semicond., 2019, 40(6): 061001. doi: 10.1088/1674-4926/40/6/061001.Export: BibTex EndNote
J. Semicond. 2019, 40 (6): 061002Yue Li, Ming Gong, Hualing Zeng. Atomically thin α-In2Se3: an emergent two-dimensional room temperature ferroelectric semiconductor[J]. Journal of Semiconductors, 2019, 40(6): 061002. doi: 10.1088/1674-4926/40/6/061002.
Y Li, M Gong, H L Zeng, Atomically thin α-In2Se3: an emergent two-dimensional room temperature ferroelectric semiconductor[J]. J. Semicond., 2019, 40(6): 061002. doi: 10.1088/1674-4926/40/6/061002.Export: BibTex EndNote
Room temperature ferroelectric thin films are the key element of high-density nonvolatile memories in modern electronics. However, with the further miniaturization of the electronic devices beyond the Moore’s law, conventional ferroelectrics suffer great challenge arising from the critical thickness effect, where the ferroelectricity is unstable if the film thickness is reduced to nanometer or single atomic layer limit. Two-dimensional (2D) materials, thanks to their stable layered structure, saturate interfacial chemistry, weak interlayer couplings, and the benefit of preparing stable ultra-thin film at 2D limit, are promising for exploring 2D ferroelectricity and related device applications. Therefore, it provides an effective approach to overcome the limitation in conventional ferroelectrics with the study of 2D ferroelectricity in van der Waals (vdW) materials. In this review article, we briefly introduce recent progresses on 2D ferroelectricity in layered vdW materials. We will highlight the study on atomically thin α-In2Se3, which is an emergent ferroelectric semiconductor with the coupled in-plane and out-of-plane ferroelectricity. Furthermore, two prototype ferroelectric devices based on ferroelectric α-In2Se3 will also be reviewed.
Synthesis, properties, and applications of large-scale two-dimensional materials by polymer-assisted deposition
J. Semicond. 2019, 40 (6): 061003Hongtao Ren, Yachao Liu, Lei Zhang, Kai Liu. Synthesis, properties, and applications of large-scale two-dimensional materials by polymer-assisted deposition[J]. Journal of Semiconductors, 2019, 40(6): 061003. doi: 10.1088/1674-4926/40/6/061003.
H T Ren, Y C Liu, L Zhang, K Liu, Synthesis, properties, and applications of large-scale two-dimensional materials by polymer-assisted deposition[J]. J. Semicond., 2019, 40(6): 061003. doi: 10.1088/1674-4926/40/6/061003.Export: BibTex EndNote
Two-dimensional (2D) materials have attracted considerable attention because of their novel and tunable electronic, optical, ferromagnetic, and chemical properties. Compared to mechanical exfoliation and chemical vapor deposition, polymer-assisted deposition (PAD) is more suitable for mass production of 2D materials owing to its good reproducibility and reliability. In this review, we summarize the recent development of PAD on syntheses of 2D materials. First, we introduce principles and processing steps of PAD. Second, 2D materials, including graphene, MoS2, and MoS2/glassy-graphene heterostructures, are presented to illustrate the power of PAD and provide readers with the opportunity to assess the method. Last, we discuss the future prospects and challenges in this research field. This review provides a novel technique for preparing 2D layered materials and may inspire new applications of 2D layered materials.
J. Semicond. 2019, 40 (4): 041901Haizhen Wang, Chen Fang, Hongmei Luo, Dehui Li. Recent progress of the optoelectronic properties of 2D Ruddlesden-Popper perovskites[J]. Journal of Semiconductors, 2019, 40(4): 041901. doi: 10.1088/1674-4926/40/4/041901.
H Z Wang, C Fang, H M Luo, D H Li, Recent progress of the optoelectronic properties of 2D Ruddlesden-Popper perovskites[J]. J. Semicond., 2019, 40(4): 041901. doi: 10.1088/1674-4926/40/4/041901.Export: BibTex EndNote
Two-dimensional (2D) hybrid organic-inorganic perovskites have recently attracted attention due to their layered nature, naturally formed quantum well structure, large exciton binding energy and especially better long-term environmental stability compared with their three-dimensional (3D) counterparts. In this report, we present a brief overview of the recent progress of the optoelectronic applications in 2D perovskites. The layer number dependent physical properties of 2D perovskites will first be introduced and then the different synthetic approaches to achieve 2D perovskites with different morphologies will be discussed. The optical, optoelectronic properties and self-trapped states in 2D perovskites will be described, which are indispensable for designing the new device structures with novel functionalities and improving the device performance. Subsequently, a brief summary of the advantages and the current research status of the 2D perovskite-based heterostructures will be illustrated. Finally, a perspective of 2D perovskite materials is given toward their material synthesis and novel device applications.
J. Semicond. 2019, 40 (1): 011801H. F. Mohamed, Changtai Xia, Qinglin Sai, Huiyuan Cui, Mingyan Pan, Hongji Qi. Growth and fundamentals of bulk β-Ga2O3 single crystals[J]. Journal of Semiconductors, 2019, 40(1): 011801. doi: 10.1088/1674-4926/40/1/011801.
H F Mohamed, C T Xia, Q L Sai, H Y Cui, M Y Pan, H J Qi, Growth and fundamentals of bulk β-Ga2O3 single crystals[J]. J. Semicond., 2019, 40(1): 011801. doi: 10.1088/1674-4926/40/1/011801.Export: BibTex EndNote
The rapid development of bulk β-Ga2O3 crystals has attracted much attention to their use as ultra-wide bandgap materials for next-generation power devices owing to its large bandgap (~ 4.9 eV) and large breakdown electric field of about 8 MV/cm. Low cost and high quality of large β-Ga2O3 single-crystal substrates can be attained by melting growth techniques widely used in the industry. In this paper, we first present an overview of the properties of β-Ga2O3 crystals in bulk form. We then describe the various methods for producing bulk β-Ga2O3 crystals and their applications. Finally, we will present a future perspective of the research in the area in the area of single crystal growth.
J. Semicond. 2019, 40 (1): 011802Hang Dong, Huiwen Xue, Qiming He, Yuan Qin, Guangzhong Jian, Shibing Long, Ming Liu. Progress of power field effect transistor based on ultra-wide bandgap Ga2O3 semiconductor material[J]. Journal of Semiconductors, 2019, 40(1): 011802. doi: 10.1088/1674-4926/40/1/011802.
H Dong, H W Xue, Q M He, Y Qin, G Z Jian, S B Long, M Liu, Progress of power field effect transistor based on ultra-wide bandgap Ga2O3 semiconductor material[J]. J. Semicond., 2019, 40(1): 011802. doi: 10.1088/1674-4926/40/1/011802.Export: BibTex EndNote
As a promising ultra-wide bandgap semiconductor, gallium oxide (Ga2O3) has attracted increasing attention in recent years. The high theoretical breakdown electrical field (8 MV/cm), ultra-wide bandgap (~ 4.8 eV) and large Baliga’s figure of merit (BFOM) of Ga2O3 make it a potential candidate material for next generation high-power electronics, including diode and field effect transistor (FET). In this paper, we introduce the basic physical properties of Ga2O3 single crystal, and review the recent research process of Ga2O3 based field effect transistors. Furthermore, various structures of FETs have been summarized and compared, and the potential of Ga2O3 is preliminary revealed. Finally, the prospect of the Ga2O3 based FET for power electronics application is analyzed.
J. Semicond. 2019, 40 (1): 011803Hong Zhou, Jincheng Zhang, Chunfu Zhang, Qian Feng, Shenglei Zhao, Peijun Ma, Yue Hao. A review of the most recent progresses of state-of-art gallium oxide power devices[J]. Journal of Semiconductors, 2019, 40(1): 011803. doi: 10.1088/1674-4926/40/1/011803.
H Zhou, J C Zhang, C F Zhang, Q Feng, S L Zhao, P J Ma, Y Hao, A review of the most recent progresses of state-of-art gallium oxide power devices[J]. J. Semicond., 2019, 40(1): 011803. doi: 10.1088/1674-4926/40/1/011803.Export: BibTex EndNote
Until very recently, gallium oxide (Ga2O3) has aroused more and more interests in the area of power electronics due to its ultra-wide bandgap of 4.5–4.8 eV, estimated critical field of 8 MV/cm and decent intrinsic electron mobility limit of 250 cm2/(V·s), yielding a high Baliga’s figures-of-merit (FOM) of more than 3000, which is several times higher than GaN and SiC. In addition to its excellent material properties, potential low-cost and large size substrate through melt-grown methodology also endows β-Ga2O3 more potential for future low-cost power devices. This article focuses on reviewing the most recent advances of β-Ga2O3 based power devices. It will be starting with a brief introduction to the material properties of β-Ga2O3 and then the growth techniques of its native substrate, followed by the thin film epitaxial growth. The performance of state-of-art β-Ga2O3 devices, including diodes and FETs are fully discussed and compared. Finally, potential solutions to the challenges of β-Ga2O3 are also discussed and explored.
A review of β-Ga2O3 single crystal defects, their effects on device performance and their formation mechanism
J. Semicond. 2019, 40 (1): 011804Bo Fu, Zhitai Jia, Wenxiang Mu, Yanru Yin, Jian Zhang, Xutang Tao. A review of β-Ga2O3 single crystal defects, their effects on device performance and their formation mechanism[J]. Journal of Semiconductors, 2019, 40(1): 011804. doi: 10.1088/1674-4926/40/1/011804.
B Fu, Z T Jia, W X Mu, Y R Yin, J Zhang, X T Tao, A review of β-Ga2O3 single crystal defects, their effects on device performance and their formation mechanism[J]. J. Semicond., 2019, 40(1): 011804. doi: 10.1088/1674-4926/40/1/011804.Export: BibTex EndNote
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.
J. Semicond. 2019, 40 (1): 011805Xiangqian Xiu, Liying Zhang, Yuewen Li, Zening Xiong, Rong Zhang, Youdou Zheng. Application of halide vapor phase epitaxy for the growth of ultra-wide band gap Ga2O3[J]. Journal of Semiconductors, 2019, 40(1): 011805. doi: 10.1088/1674-4926/40/1/011805.
X Q Xiu, L Y Zhang, Y W Li, Z N Xiong, R Zhang, Y D Zheng, Application of halide vapor phase epitaxy for the growth of ultra-wide band gap Ga2O3[J]. J. Semicond., 2019, 40(1): 011805. doi: 10.1088/1674-4926/40/1/011805.Export: BibTex EndNote
Halide vapor phase epitaxy (HVPE) is widely used in the semiconductor industry for the growth of Si, GaAs, GaN, etc. HVPE is a non-organic chemical vapor deposition (CVD) technique, characterized by high quality growth of epitaxial layers with fast growth rate, which is versatile for the fabrication of both substrates and devices with wide applications. In this paper, we review the usage of HVPE for the growth and device applications of Ga2O3, with detailed discussions on a variety of technological aspects of HVPE. It is concluded that HVPE is a promising candidate for the epitaxy of large-area Ga2O3 substrates and for the fabrication of high power β-Ga2O3 devices.
J. Semicond. 2018, 39 (10): 101001Dan Lu, Yiming He, Zhaosong Li, Lingjuan Zhao, Wei Wang. InP-based monolithically integrated few-mode devices[J]. Journal of Semiconductors, 2018, 39(10): 101001. doi: 10.1088/1674-4926/39/10/101001.
D Lu, Y M He, Z S Li, L J Zhao, W Wang, InP-based monolithically integrated few-mode devices[J]. J. Semicond., 2018, 39(10): 101001. doi: 10.1088/1674-4926/39/10/101001.Export: BibTex EndNote
Mode-division multiplexing (MDM) has become an increasingly important technology to further increase the transmission capacity of both optical-fiber-based communication networks, data centers and waveguide-based on-chip optical interconnects. Mode manipulation devices are indispensable in MDM system and have been widely studied in fiber, planar lightwave circuits, and silicon and InP based platforms. InP-based integration technology provides the easiest accessibility to bring together the functions of laser sources, modulators, and mode manipulation devices into a single chip, making it a promising solution for fully integrated few-mode transmitters in the MDM system. This paper reviews the recent progress in InP-based mode manipulation devices, including the few-mode converters, multiplexers, demultiplexers, and transmitters. The working principle, structures, and performance of InP-based few-mode devices are discussed.
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