Ga2O3功率器件研究现状和发展趋势

氧化镓(Ga2O3)超宽禁带半导体材料在高频大功率器件领域具有巨大的应用潜力和前景,近几年已成为国内外研发的热点.概述了Ga2O3半导体材料在功率器件应用领域的特性优势和不足,重点介绍了日本、美国和国内的Ga2O3功率半导体器件的研发现状.详细介绍了目前Ga2O3肖特基势垒二极管(SBD)、Ga2O3金属氧化物半导体场效应晶体管(MOSFET)以及新型Ga2O3功率器件的最新研究成果.归纳出提高Ga2O3单晶和外延材料质量、优化Ga2O3功率器件结构和制造工艺是Ga2O3功率器件未来的主要发展趋势,高功率、高效率、高可靠性和低成本是Ga2O3功率器件未来的主要发展目标.最后总结了我国与美国、日本在Ga2O3功率半导体领域的技术发展差距,以及对未来我国在Ga2O3功率半导体技术方面的发展提出了建议.     

超宽禁带半导体α-Ga2O3肖特基二极管仿真研究

氧化镓(Ga₂O₃)作为一种新型的超宽禁带半导体材料,与目前常用的半导体材料SiC和GaN相比,具有更大的禁带宽度、更高的击穿场强等优良特性。设计了一种基于α-Ga₂O₃的垂直型肖特基二极管(SBD),采用场板终端结构降低阳极边缘电场强度,研究了不同绝缘材料下阳极附近的电场分布,并探讨了场板结构与长度对其击穿特性的影响。仿真结果表明,在选取HfO₂作为α-Ga₂O₃垂直型SBD场板结构的绝缘材料时,场板结构可以增大该器件的反向击穿电压,最大反向击穿电压可达约1 100 V,对于现实中制备α-Ga₂O₃ SBD具有非常重要的参考意义。     

基于HfO2栅介质的Ga2O3 MOSFET器件研制

采用金属有机化学气相沉积(MOCVD)方法在(010) Fe掺杂半绝缘Ga2O3同质衬底上外延得到n型β-Ga2O3薄膜材料,材料结构包括400 nm的非故意掺杂Ga2O3缓冲层和40 nm的Si掺杂Ga2O3沟道层.基于掺杂浓度为2.0×1018 cm-3的n型β-Ga2O3薄膜材料,采用原子层沉积的25 nm的HfO2作为栅下绝缘介质层,研制出Ga2O3金属氧化物半导体场效应晶体管(MOSFET).器件展示出良好的电学特性,在栅偏压为8V时,漏源饱和电流密度达到42 mA/mm,器件的峰值跨导约为3.8 mS/mm,漏源电流开关比达到108.此外,器件的三端关态击穿电压为113 V.采用场板结构并结合n型Ga2O3沟道层结构优化设计能进一步提升器件饱和电流和击穿电压等电学特性.     

β-Ga2O3材料在半导体技术领域的应用现状北大核心

单斜晶系氧化镓（β-Ga2O3）超宽带半导体材料具有优良的电学、光学特性以及较高的物理化学稳定性,在大功率器件、紫外探测器以及气体传感器等技术领域具有巨大的应用前景,近年来已成为国际研发的热点。概述了β-Ga2O3半导体材料的特性优势。综述了β-Ga2O3在功率半导体器件、紫外探测器、气体传感器、衬底材料以及GaN器件栅介质领域的研发和应用现状。最后,分析了β-Ga2O3材料在半导体技术领域的应用前景,指出大功率半导体器件领域和日盲深紫外探测器领域将是未来发展的重要方向。     

基于改进水热法的Ga2O3纳米棒制备及表征

采用改进的水热法对衬底进行预处理,分别在单晶硅Si(111)和蓝宝石C(0001)衬底上生长一层Ga2O3籽晶层.籽晶层退火处理后放入Ga2(NO3)3溶液高压反应釜内进行水热反应,待反应结束进行二次退火,成功制备出了Ga2 O3纳米棒.研究了不同温度对籽晶层和Ga2 O3纳米棒的影响,通过扫描电子显微镜(SEM)和X...     

新一代功率半导体β-Ga_2O_3器件进展与展望

Ga_2O_3是一种新兴的超宽禁带半导体材料,具有超宽带隙4.8 eV、超高理论击穿电场8 MV/cm以及超高的Baliga品质因数等优良特性,作为下一代高功率器件材料其越来越受到人们的关注。首先,回顾了宽禁带半导体材料β-Ga_2O_3的基本性质,包括β-Ga_2O_3的晶体结构和电学性质,简述了基于β-Ga_2O_3制造的功率器件,主要包括肖特基势垒二极管(SBD)和金属-氧化物-半导体场效应晶体管(MOSFET)。总结回顾了β-Ga_2O_3SBD和MOSFET近年来的研究进展,比较了不同结构器件的特性,并分析了目前β-Ga_2O_3功率器件存在的问题。分析表明,β-Ga_2O_3用于高功率和高压电子器件具有巨大潜力。     

氧化镓基肖特基势垒二极管的研究进展

Ga₂O₃是一种新型宽禁带半导体材料,禁带宽度约为4.8 eV,临界击穿电场理论上可高达8 MV/cm, Baliga优值超过3 000,因此在制作功率器件方面有很大的潜力。Ga₂O₃是继SiC和GaN之后制作高性能半导体器件的优选材料,近年来受到了广泛的关注。介绍了Ga₂O₃材料的基本物理性质,分析了Ga₂O₃基肖特基势垒二极管(SBD)的优势及存在的问题。重点从器件工艺、结构和边缘终端技术等角度评述了优化Ga₂O₃基SBD性能的方法,并对Ga₂O₃基SBD的进一步发展趋势进行了展望。     

阳极刻蚀提升Ga2O3肖特基势垒二极管击穿特性

提出了一种采用阳极刻蚀提升Ga₂O₃肖特基势垒二极管(SBD)击穿特性的新方法。基于氢化物气相外延(HVPE)法生长的Ga₂O₃材料制备了Ga₂O₃纵向SBD。在完成阳极制备后,对阳极以外的Ga₂O₃漂移区进行了不同深度的刻蚀,刻蚀完成后,在器件表面生长了SiO₂介质层,随后制备了场板结构。测试结果显示,刻蚀后器件的比导通电阻小幅上升,而反向击穿电压均大幅提升。刻蚀深度为300 nm的β-Ga₂O₃ SBD具有最优特性,其比导通电阻(R_{on, sp})为2.5 mΩ·cm²,击穿电压(V_br)为1 410 V,功率品质因子(FOM)为795 MW/cm²。该研究为高性能Ga₂O₃ SBD的制备提供了一种新方法。     

Machine Vision Based on an Ultra-Wide Bandgap 2D Semiconductor AsSbO3

Facing the future development trend of miniaturization and intelligence of electronic devices, solar-blind photodetectors based on ultrawide-bandgap 2D semiconductors have the advantages of low dark current, and high signal-to-noise ratio, as well as the features of micro-nanometer miniaturization and multi-functionalization of 2D material devices, which have potential applications in the photoelectric sensor part of high-performance machine vision systems. This study reports a 2D oxide semiconductor, AsSbO₃, with an ultrawide bandgap (4.997 eV for monolayer and 4.4 eV for multilayer) to be used to fabricate highly selective solar-blind UV photodetectors, of which the dark current as low as 100 fA and rejection ratio of UV-C and UV-A reaches 7.6 × 10³. Under 239 nm incident light, the responsivity is 105 mA W⁻¹ and the detectivity is 7.58 × 10¹² Jones. Owing to the remarkable anisotropic crystal structure, AsSbO₃ also shows significant linear dichroism and nonlinear optical properties. Finally, a simple machine vision system is simulated by combining the real-time imaging function in solar-blind UV with a convolutional neural network. This study enriches the material system of ultrawide-bandgap 2D semiconductors and provides insight into the future development of high-performance solar-blind UV optoelectronic devices.     

3D Solar‐Blind Ga2O3 Photodetector Array Realized Via Origami Method

A 3D solar‐blind photodetector array is realized from amorphous Ga₂O₃ films grown on polyethylene terephthalate substrates via an origami route. The photodetector cells exhibit a dark current of 0.17 nA, and the peak responsivity is about 8.9 A W^?1 at 250 nm with a quantum efficiency of 4450%. The photodetector shows a distinct cut‐off wavelength at 268 nm with a solar‐blind ratio of more than two orders of magnitude (photocurrent ratio between 250 nm/300 nm). The photodetector cells reveal excellent electrical stability after thousands of bending cycles. All the photodetector cells of the 3D photodetector array have a highly consistent performance. In addition, the device can execute the functions of capturing a real‐time light trajectory and identifying multipoint light spatial distribution, which cannot be achieved in all the previously reported 2D solar‐blind photodetectors. The results suggest new pathways to fabricate 3D photodetectors from conventional semiconductor films, which may find potential applications in optical positioning, tracking, imaging and communications, etc.     

High Purity and Large-scale Preparation of β-Ga2O3 Nanowires and Nanosheets by CVD and Their Raman and Photoluminescence Characteristics

Ga2O3 nano-structures, nanowires and nanosheets are produced on Au pre coated（111） silicon substrates with chemical vapor deposition（CVD） technique. By evaporating pure Ga powder in the H2O atmosphere under ambient pressure the large-scale preparation of β-Ga2O3 with monoclinic crystalline structure is achieved. The crystalline structures and morphologies of produced Ga2O3 nano-structures are characterized by means of scanning electron microscope（SEM）, X-ray diffraction（XRD）, selected area electron diffraction （SAED） and transmission electron microscope（TEM）. Raman spectrum reveals the typical vibration modes of Ga2O3 The vibration mode shifts corresponding to Ga2O3 nano-structures are not found. Two distinguish photoluminescence（PL） emissions are found at about 399 nm and 469 nm owing to the VO-VGa excitation and VO-VGaO excitation, respectively. The growth mechanisms of Ga2O3 nanowires and nanosheets are discussed with vapor liquid-solid（VLS） and vapor-solid（VS） mechanisms.     

Investigation of β-Ga2O3 thick films grown on c-plane sapphire via carbothermal reduction

We investigated the influence of the growth temperature, O₂ flow, molar ratio between Ga₂O₃ powder and graphite powder on the structure and morphology of the films grown on the c-plane sapphire (0001) substrates by a carbothermal reduction method. Experimental results for the heteroepitaxial growth of β-Ga₂O₃ illustrate that β-Ga₂O₃ growth by the carbothermal reduction method can be controlled. The optimal result was obtained at a growth temperature of 1050 °C. The fastest growth rate of β-Ga₂O₃ films was produced when the O₂ flow was 20 sccm. To guarantee that β-Ga₂O₃ films with both high-quality crystal and morphology properties, the ideal molar ratio between graphite powder and Ga₂O₃ powder should be set at 10 : 1.     

氮化Si基ZnO/Ga_2O_3制备GaN薄膜

利用射频磁控溅射法在Si衬底上先溅射ZnO缓冲层,接着溅射Ga2O3薄膜,然后ZnO/Ga2O3膜在管式炉中常压下通氨气进行氮化,反应自组生成GaN薄膜。XRD测量结果表明,利用该方法制备的GaN薄膜是沿c轴方向择优生长的六角纤锌矿多晶结构的薄膜,利用SEM观测了其表面形貌,PL测量结果发现了位于351nm处的室温光致发光峰。     

Tin Doping Induced High-Performance Solution-Processed Ga2O3 Photosensor toward Neuromorphic Visual System

Ga₂O₃ is an emerging wide-bandgap semiconductor with high deep ultraviolet absorption, tunable persistent photoconductivity, and excellent stability toward electric fields, making it a promising component for neuromorphic visual systems (NVSs). However, Ga₂O₃-based photosensors with high responsivity and long response decay times are required for efficient NVSs. A solution-processed doping strategy for fabrication of Ga₂O₃ is proposed with tin foil as a dopant source. Tin-doped Ga₂O₃ (Ga₂O₃:Sn) photosensors are obtained with ultrahigh responsivity and extremely long response decay times. These behaviors are attributed to substitutional tin and oxygen vacancies that modulate defect-related hole trapping. High-performance Ga₂O₃:Sn photosensors can mimic photonic synaptic behaviors and image pre-processing functions. NVSs based on a Ga₂O₃:Sn photonic synapse array perform pattern recognition with an accuracy of 97.3% under an unprecedented low-light pulse stimuli of 0.5 µW cm⁻². This work provides a low-cost solution-processed approach to ultrasensitive Ga₂O₃:Sn NVSs and will facilitate developments in artificial intelligence technology.     

Si基氨化ZnO／Ga2O3薄膜制备GaN纳米线

利用射频磁控溅射法在Si(111)衬底上溅射ZnO中间层和Ga2O3薄膜，然后在管式炉中常压下通氨气对ZnO/Ga2O3薄膜进行氨化，高温下ZnO层在氨气气氛中挥发，而Ga2O3薄膜和氨气反应合成出GaN纳米线．X射线衍射测量结果表明利用该方法制备的GaN纳米线具有沿c轴方向择优生长的六角纤锌矿结构．利用扫描电子显微镜、透射电子显微镜、傅里叶红外透射谱、能量弥散谱及选区电子衍射观测并分析了样品的形貌、成分和晶格结构．研究发现ZnO层的挥发有利于Ga2O3和NH3反应合成GaN纳米线．     

Cr_2O_3掺杂对钡硼硅微晶玻璃的性能影响

采用固相合成法制备了高膨胀系数钡硼硅微晶玻璃材料。通过对该微晶玻璃进行X线衍射仪(XRD)、扫描电子显微镜(SEM)测试分析研究铬掺杂对BaO-B2O3-SiO2力、热、电性能及微观机理的影响。结果显示,热膨胀系数与介电损耗随Cr2O3含量增加而增大,研究表明,加入Cr2O3会促进该体系晶粒的生长,并促使晶相由石英晶相转变为方石英晶相,方石英热膨胀系数较高,其晶相含量增多导致热膨胀系数增大。该体系Cr2O3质量分数为0.5%时,制备出具有较高热膨胀系数(18.44×10-6/℃),较高抗弯强度(187 MPa),较低相对介电常数(5.5)的封装材料。     

Source-field-plated Ga2O3 MOSFET with a breakdown voltage of 550 V

Ga_2O_3 metal–oxide–semiconductor field-effect transistors(MOSFETs) with high-breakdown characteristics were fabricated on a homoepitaxial n-typed β-Ga_2O_3 film, which was grown by metal organic chemical vapor deposition(MOCVD) on an Fedoped semi-insulating(010) Ga_2O_3 substrate. The structure consisted of a 400 nm unintentionally doped(UID) Ga_2O_3 buffer layer and an 80 nm Si-doped channel layer. A high k HfO_2 gate dielectric film formed by atomic layer deposition was employed to reduce the gate leakage. Moreover, a source-connected field plate was introduced to enhance the breakdown characteristics. The drain saturation current density of the fabricated device reached 101 mA/mm at V_gs of 3 V. The off-state current was as low as 7.1 ×10^-11 A/mm, and the drain current I_ON/I_OFF ratio reached 10~9. The transistors exhibited three-terminal off-state breakdown voltages of 450 and 550 V, corresponding to gate-to-drain spacing of 4 and 8 μm, respectively.     

A review of β-Ga2O3 single crystal defects,their effects on device performance and their formation mechanism

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.