Low-Temperature Growth of Epitaxial Semiconductor Nanostructures and Films

2011 ◽  
Vol 1308 ◽  
Author(s):  
Alp T. Findikoglu ◽  
Daniel E. Perea ◽  
S. T. Picraux

ABSTRACTThe growth of epitaxial semiconductor nanostructures and films at low temperatures is important for semiconductor technology because it allows the possibility of monolithically integrating different high-performance single-crystalline semiconductor structures directly onto low cost technologically important substrates. At sufficiently low temperatures this can enable, for example, Si or Ge device fabrication on flexible substrates such as plastics. We have studied the reduced-temperature liquid-mediated growth of Ge nanostructures and films on crystalline template layers on non-single-crystalline substrates in a low-pressure chemical vapor deposition (LPCVD) system. The heteroepitaxial process is implemented by the Au seeded vapor-liquidsolid (VLS) catalytic growth technique with germane below 400 ºC. Crystalline template layers were prepared with ion-beam-assisted-deposition (IBAD) texturing and electron-beam evaporation on glass substrates. A thin layer of e-beam evaporated Au forms the catalyst layer, upon which we grew Ge films at 386 ºC. Scanning electron microscopy and x-ray diffraction results indicated that both Ge islands and nanowires grew heteroepitaxially on the crystalline template layers on glass substrates with good alignment over large areas.

2019 ◽  
Vol 52 (4) ◽  
pp. 898-902 ◽  
Author(s):  
Yongkuan Li ◽  
Sicong Sun ◽  
Ying Gao ◽  
Yao Yao ◽  
Eduard Galstyan ◽  
...  

Low texture spreads of single-crystalline-like materials are critical for high performance of low-cost flexible semiconductors and second-generation high-temperature superconductors based on metal foils. For texture improvement, a single-crystalline-like Ag film is epitaxially grown on an ion-beam-assisted deposition TiN substrate using magnetron sputtering. Ultra-low texture spreads are found in the thin Ag film (∼330 nm), with an out-of-plane texture spread (Δω) of ∼1.03° and an in-plane texture spread (Δϕ) of ∼1.34°. Compared with the texture spreads of the TiN substrate, Δω and Δϕ of the Ag film are reduced by ∼42 and ∼79%, respectively. Applying this Ag buffer, the texture spreads of a single-crystalline-like Ge film are reduced by ∼37% (Δω) and ∼36% (Δϕ). Factors contributing to the texture improvement by Ag are studied using single-crystalline-like Ag films with various thicknesses.


2004 ◽  
Vol 809 ◽  
Author(s):  
R. Loo ◽  
R. Delhougne ◽  
P. Meunier-Beillard ◽  
M. Caymax ◽  
P. Verheyen ◽  
...  

ABSTRACTTensile strained Si on SiGe Strain Relaxed Buffers (SRB) is an interesting candidate to increase both electron and hole mobility which results in improved device performance. Most of this work was/is based on thick (several μm), step-graded SRBs with or without Chemical Mechanical Polishing (CMP) planarisation. This approach bears several disadvantages such as issues with STI formation in the thick SiGe structure, and considerable self-heating effects due to the lower thermal conductivity of the SiGe material. Further, pMOS improvement requires SRBs with high Ge contents (> 30 %), which complicates device fabrication even more. To overcome these issues, we developed a new and cost efficient type of thin SRB (∼200 nm). The concept is based on the introduction of a thin carbon-containing layer during growth of a constant composition SiGe layer. The process relies on standard Chemical Vapor Deposition epitaxial technology without need for CMP. It is designed to allow both non-selective growth on blanket wafers and selective growth in the active area of structured wafers with Shallow Trench Isolation (STI). The selective epitaxial process for strained Si on thin SRBs proposed here, allows relatively simple and cost-effective fabrication of strained Si layers on existing STI structures without any process modification. Further, it offers a very flexible fabrication scheme to independently improve nMOS and pMOS devices. The SRB quality is comparable to the best reported in literature so far, with 70 % and 53 % mobility enhancements for long channel nMOSFETs on 22 % Ge SRBs grown on blanket and STI patterned wafers, respectively.


Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 545
Author(s):  
Yi Zhang ◽  
Wei Jiang ◽  
Dezhi Feng ◽  
Chenguang Wang ◽  
Yi Xu ◽  
...  

2D molybdenum disulfide (MoS2)-based thin film transistors are widely used in biosensing, and many efforts have been made to improve the detection limit and linear range. However, in addition to the complexity of device technology and biological modification, the compatibility of the physical device with biological solutions and device reusability have rarely been considered. Herein, we designed and synthesized an array of MoS2 by employing a simple-patterned chemical vapor deposition growth method and meanwhile exploited a one-step biomodification in a sensing pad based on DNA tetrahedron probes to form a bio-separated sensing part. This solves the signal interference, solution erosion, and instability of semiconductor-based biosensors after contacting biological solutions, and also allows physical devices to be reused. Furthermore, the gate-free detection structure that we first proposed for DNA (BRCA1) detection demonstrates ultrasensitive detection over a broad range of 1 fM to 1 μM with a good linear response of R2 = 0.98. Our findings provide a practical solution for high-performance, low-cost, biocompatible, reusable, and bio-separated biosensor platforms.


Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 267
Author(s):  
Minyu Bai ◽  
Zhuoman Wang ◽  
Jijie Zhao ◽  
Shuai Wen ◽  
Peiru Zhang ◽  
...  

Weak absorption remains a vital factor that limits the application of two-dimensional (2D) materials due to the atomic thickness of those materials. In this work, a direct chemical vapor deposition (CVD) process was applied to achieve 2D MoS2 encapsulation onto the silicon nanopillar array substrate (NPAS). Single-layer 2D MoS2 monocrystal sheets were obtained, and the percentage of the encapsulated surface of NPAS was up to 80%. The reflection and transmittance of incident light of our 2D MoS2-encapsulated silicon substrate within visible to shortwave infrared were significantly reduced compared with the counterpart planar silicon substrate, leading to effective light trapping in NPAS. The proposed method provides a method of conformal deposition upon NPAS that combines the advantages of both 2D MoS2 and its substrate. Furthermore, the method is feasible and low-cost, providing a promising process for high-performance optoelectronic device development.


1997 ◽  
Vol 471 ◽  
Author(s):  
D. Endisch ◽  
K. Barth ◽  
J. Lau ◽  
G. Peterson ◽  
A. E. Kaloyeros ◽  
...  

ABSTRACTSrS:Ce is an important material for full color electroluminescent (EL) flat panel displays. Using a combination of SrS:Ce/ZnS:Mn and appropriate color filters high quality full color displays have been demonstrated [1]. Major issues for commercially viable process integration of SrS:Ce are the combination of high luminance, high growth rate, and process temperatures below 600°C for compatibility with low cost glass substrates. This work describes the process development and optimization of metal-organic chemical vapor deposition (MOCVD) of SrS:Ce. MOCVD is a promising candidate for deposition of SrS:Ce because it can provide the required growth rates and allows control of crystal structure and stoichiometry. Growth of SrS:Ce was performed in the temperature range from 400°C to 530°C using Sr(tmhd)2, Ce(tmhd)4, and H2S as precursors. The structure of the SrS:Ce was found to be strongly dependent on the H2S flow. A brightness of 15 fL and an efficiency of 0.22 lm/W has been achieved (40 V above threshold voltage, 60 Hz AC). Film analysis included Rutherford backscattering (RBS), X-ray diffraction (XRD), atomic force microscopy (AFM), and EL measurements. Results on the correlation between process parameters, film structure, grain size and EL performance will be presented.


2015 ◽  
Vol 3 (31) ◽  
pp. 8074-8079 ◽  
Author(s):  
Changyong Lan ◽  
Chun Li ◽  
Yi Yin ◽  
Huayang Guo ◽  
Shuai Wang

Single-crystalline GeS nanoribbons were synthesized by chemical vapor deposition for the first time. The nanoribbon photodetectors respond to the entire visible incident light with a response edge at around 750 nm and a high responsivity, indicating their promising application for high performance broadband visible-light photo-detection.


1997 ◽  
Vol 51 (6) ◽  
pp. 880-882 ◽  
Author(s):  
Brian R. Stallard ◽  
Robert K. Rowe ◽  
Arnold J. Howard ◽  
G. Ronald Hadley ◽  
Gregory A. Vawter ◽  
...  

Miniature, low-cost sensors are in demand for a variety of applications in industry, medicine, and environmental sciences. As a first step in developing such a sensor, we have etched a grating into a GaAs rib waveguide to serve as a wavelength-dispersive element. The device was fabricated with the techniques of metal-organic chemical vapor deposition, electron-beam lithography, optical lithography, and reactive ion-beam etching. While full integration is the eventual goal of this work, for the present, a functional spectrometer was constructed with the addition of a discrete source, sample cell, lenses, and detector. The waveguide spectrometer has a spectral resolution of 7.5 nm and a spectral dispersion of 0.11°/ nm. As presently configured, it functions in the spectral range of 1500 to 1600 nm. A demonstration of the analytical capability of the waveguide spectrometer is presented. The problem posed is the determination of diethanol amine in an ethanol solution (about 10 to 100 g/L). This procedure involves the detection of the first overtone of the NH stretch at 1545 nm in a moderately absorbing solvent background. The standard error of prediction for the determination was 5.4 g/L.


2012 ◽  
Vol 1439 ◽  
pp. 139-144 ◽  
Author(s):  
Nima Mohseni Kiasari ◽  
Saeid Soltanian ◽  
Bobak Gholamkhass ◽  
Peyman Servati

ABSTRACTZinc oxide (ZnO) nanowires (NW) are grown on both silicon and sapphire substrates using conventional chemical vapor deposition (CVD) system. As-grown nanostructures are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) as well as energy dispersive spectroscopy (EDS) and the results confirm high-quality c-axis growth of single-crystalline zinc oxide nanowires. Nanowire are dispersed in solvent and then placed between micro-patterned gold electrodes fabricated on silicon wafers using low cost and scalable dielectrophoresis (DEP) process for fabrication of oxygen and humidity sensors. These sensors are characterized in a vacuum chamber connected to a semiconductor analyzer. Current-voltage characteristics of each device are systematically investigated under different hydrostatic pressure of various gaseous environments such as nitrogen, argon, dry and humid air. It is observed that the electrical conductivity of the nanowires is significantly dependent on the number of oxygen and water molecules adsorbed to the surface of the metal oxide nanowire. These results are critical for development of low cost metal oxide sensors for high performance ubiquitous environmental sensors of oxygen and humidity.


Science ◽  
2018 ◽  
Vol 362 (6416) ◽  
pp. 817-821 ◽  
Author(s):  
Joo Song Lee ◽  
Soo Ho Choi ◽  
Seok Joon Yun ◽  
Yong In Kim ◽  
Stephen Boandoh ◽  
...  

Although polycrystalline hexagonal boron nitride (PC-hBN) has been realized, defects and grain boundaries still cause charge scatterings and trap sites, impeding high-performance electronics. Here, we report a method of synthesizing wafer-scale single-crystalline hBN (SC-hBN) monolayer films by chemical vapor deposition. The limited solubility of boron (B) and nitrogen (N) atoms in liquid gold promotes high diffusion of adatoms on the surface of liquid at high temperature to provoke the circular hBN grains. These further evolve into closely packed unimodal grains by means of self-collimation of B and N edges inherited by electrostatic interaction between grains, eventually forming an SC-hBN film on a wafer scale. This SC-hBN film also allows for the synthesis of wafer-scale graphene/hBN heterostructure and single-crystalline tungsten disulfide.


2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Ming Fang ◽  
Ning Han ◽  
Fengyun Wang ◽  
Zai-xing Yang ◽  
SenPo Yip ◽  
...  

III–V semiconductor nanowire (NW) materials possess a combination of fascinating properties, including their tunable direct bandgap, high carrier mobility, excellent mechanical flexibility, and extraordinarily large surface-to-volume ratio, making them superior candidates for next generation electronics, photonics, and sensors, even possibly on flexible substrates. Understanding the synthesis, property manipulation, and device integration of these III–V NW materials is therefore crucial for their practical implementations. In this review, we present a comprehensive overview of the recent development in III–V NWs with the focus on their cost-effective synthesis, corresponding property control, and the relevant low-operating-power device applications. We will first introduce the synthesis methods and growth mechanisms of III–V NWs, emphasizing the low-cost solid-source chemical vapor deposition (SSCVD) technique, and then discuss the physical properties of III–V NWs with special attention on their dependences on several typical factors including the choice of catalysts, NW diameters, surface roughness, and surface decorations. After that, we present several different examples in the area of high-performance photovoltaics and low-power electronic circuit prototypes to further demonstrate the potential applications of these NW materials. Towards the end, we also make some remarks on the progress made and challenges remaining in the III–V NW research field.


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