| Si-based semiconductor materials are the foundation of the modern microelectronics industry and the information society,and are important technical guarantees for the national economy and the people's livelihood and the country's core competitiveness.In 2017,China imported 260.1 billion US dollars of integrated circuit chips.In 2018,the import volume exceeded 300 billion US dollars,equivalent to RMB 2.1 trillion,which exceeded the trading of bulk commodities such as crude oil.To this end,it is particularly important to increase the research and development of silicon-based semiconductor materials and explore silicon-based semiconductor high-performance devices with independent intellectual property rights.Silicon and germanium are the most important semiconductor materials in the field of electronic information.In 1947,Bell Labs developed the first germanium transistor,which laid the foundation for microelectronics technology.However,due to the "heat out of control" and surface passivation defects of germanium semiconductors,the related applications are limited,and the crystalline silicon semiconductor devices with more stable performance have been rapidly developed and applied,and according to Moore's Law,the number and performance of transistors doubles every 18 months.As the scale of conventional silicon transistors is gradually approaching the physical limit,the trend of simply reducing the process line width and increasing the integration density has been saturated in recent years.In the continuation of Beyond Moore's exploration,FinFETs with 3D trench architecture and higher capacitive coupling have become mainstream;in addition,in pursuit of higher carrier mobility,the use of germanium-silicon lattice stress engineering has developed "strained silicon technology";further,since germanium has the highest hole mobility in semiconductor materials,such as the ability to integrate matching hole-on-channel and electronic silicon-channel FET devices,it is expected to achieve higher mobility,lower power CMOS integrated circuit devices;finally,the Bohr radius of germanium is 24.3 nm(4.9 nm for silicon),and nanomaterials have a more pronounced quantum confinement effect at the same scale.It also provides a critical material and technology foundation for ultra-low power single-electron devices,quantum spin FETs,and efficient photodetection.At the same time,in today's post-Moore era,more and more applications beyond Moore's devices are emerging.For example,silicon-based optoelectronic integrated optical interconnects,micro-nano electromechanical sensing,and advanced thin-film electronics.Among them,new thin-film electronic devices represented by large-area flat panel display,flexible wearable devices and artificial skin sensing are gradually becoming the focus of research.However,the lithography process that can be used in large-area electronic devices is limited to a few micrometers,and it is impossible to directly implement high-performance nanowire channel FinFET structures in microelectronic devices,while flexible electronic applications also propose channels for silicon and germanium devices.To this end,exploring the large-area and reliable preparation of new crystalline silicon and germanium nanochannels,as well as the high-efficiency morphology component regulation technology is the key to breaking the performance limitations of large-area electronic devices.In addition to the "top-down"etching technique,germanium silicon nanowires can also be prepared by "bottom-up"growth.Such as Vapor-Liquid-Solid(VLS)nanowires growth model,through metal droplets catalyzed gaseous precursor to achieve nanowires growth,can be highly efficient and low-cost preparation of silicon germanium nanowires array.It has received extensive attention and research in the past years.However,gaseous supplied VLS growth modes typically produce vertical nanowire arrays that are difficult to be directly compatible with existing mainstream planar processes.In response to these fundamental problems,our group first proposed a new in-plane solid-liquid-solid(IPSLS)growth mode in the preliminary work,using amorphous silicon film as the solid precursor layer.And low-melting-point metal nano-catalytic droplets such as metal indium absorb the precursor in planar motion and grow crystalline nanowires.Through the channel guiding,the positioning,guiding and flexible topography of the nanowires are realized.Large-area nanowire array self-positioning integration can be realized in PECVD systems.Based on the above work,the work of this thesis focuses on exploring the regulation of planar silicon germanium component engineering,and its new application in the field of photoelectric detection.The following four aspects are mainly studied:1.Morphological regulation of planar Si(Ge)nanowiresThrough the systematic study of the matching relationship between low-melting metal droplets and amorphous precursors and the substrate,the "interaction" between the solid liquid interface before and after the droplets and the substrate is used to realize the spontaneous zigzag,heteroepitaxy and island chain structure growth of the nanowires,laying a foundation for the application of stretchable crystal silicon and single-electron devices.Ge nanowires were grown by using indium and tin as catalysts and amorphous germanium as precursors.In addition,Si nanowires are epitaxial grown on the R-plane of Sapphire.As a channel of silicon-on-sapphire nanowires,FinFET devices with high mobility are constructed.2.Growth and component regulation of germanium silicon alloy nanowiresMonolayer amorphous SiGe(a-Si1-xGex:H)films were deposited by PECVD and grown at low temperature(<300?)to obtain homogeneous Si1-xGex nanowires.By changing the proportion of Ge and Si in solid precursor,the composition of alloy nanowires can be controlled,and the photoelectric device of SiGe were constructed.3.Growth and regulation of germanium island silicon chain nanowiresSi Ge heterostructure nanowires were obtained by the growth of a-Si:H(top)/a-Ge:H(down)precursor.In the growth process of IPSLS,the spontaneous modulation and absorption effect of metal catalyzed droplets on the interface of Si/Ge heterogeneous layer was used to realize the periodic absorption of a-Ge:H and form the heterostructure of germanium island embedded in silicon nanowires periodically.Among them,the components,period and diameter of the germanium island silicon chain nanowire can be regulated by the design of the amorphous laminar precursor and the diameter of the catalytic droplet.Moreover,the spontaneous transformation between germanium and silicon can be completed within a few nanometers,and the interface of mutational heterojunction with high quality can be obtained,which is conducive to improving the injection ratio of electron and hole current.At the same time,the germanium silicon nanowires can be precisely located in the designated area to facilitate subsequent electrical contact and device assembly.This study lays a foundation for exploring the dynamic physical properties of new nano droplets,realizing photoelectric functions and device applications.4.Ge island Si chain heterostructure nanowire photoelectric deviceIn order to systematically study and verify the influence of morphology and composition co-regulation on the infrared photoelectric properties of Ge-Si heterostructure nanowires,an optoelectronic device with Ge quantum dots embedded in silicon nanowires was constructed.Among them,the content of Ge in the island reached?85 at.%,and the effective photoelectric response at the third generation communication wavelength of 1550 nm was realized,so as to realize high-efficiency Si-Ge photoelectric detection.It lays a foundation for the realization of high efficiency photoelectric detection of SiGe nanowires and subsequent applications of photoluminescence and electroluminescence. |
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