scholarly journals Effect of the Graded Silicon Content in SRN/SRO Multilayer Structures on the Si Nanocrystals and Si Nanopyramids Formation and Their Photoluminescence Response

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6582
Author(s):  
José Juan Avilés Bravo ◽  
Santiago Antonio Cabañas Tay ◽  
Liliana Palacios Huerta ◽  
Karla Esther González Flores ◽  
Javier Flores Méndez ◽  
...  
Keyword(s):  
Silicon Content ◽  
Chemical Vapor ◽  
Multilayer Structures ◽  
Si Substrate ◽  
Enhanced Photoluminescence ◽  
Si Nanocrystals ◽  
Pressure Chemical ◽  
Mean Size ◽  
Pl Emission ◽  
Si Nanostructures

Two multilayer (ML) structures, composed of five layers of silicon-rich oxide (SRO) with different Si contents and a sixth layer of silicon-rich nitride (SRN), were deposited by low pressure chemical vapor deposition. These SRN/SRO MLs were thermally annealed at 1100 °C for 180 min in ambient N2 to induce the formation of Si nanostructures. For the first ML structure (MLA), the excess Si in each SRO layer was about 10.7 ± 0.6, 9.1 ± 0.4, 8.0 ± 0.2, 9.1 ± 0.3 and 9.7 ± 0.4 at.%, respectively. For the second ML structure (MLB), the excess Si was about 8.3 ± 0.2, 10.8 ± 0.4, 13.6 ± 1.2, 9.8 ± 0.4 and 8.7 ± 0.1 at.%, respectively. Si nanopyramids (Si-NPs) were formed in the SRO/Si substrate interface when the SRO layer with the highest excess silicon (10.7 at.%) was deposited next to the MLA substrate. The height, base and density of the Si-NPs was about 2–8 nm, 8–26 nm and ~6 × 1011 cm−2, respectively. In addition, Si nanocrystals (Si-ncs) with a mean size of between 3.95 ± 0.20 nm and 2.86 ± 0.81 nm were observed for the subsequent SRO layers. Meanwhile, Si-NPs were not observed when the excess Si in the SRO film next to the Si-substrate decreased to 8.3 ± 0.2 at.% (MLB), indicating that there existed a specific amount of excess Si for their formation. Si-ncs with mean size of 2.87 ± 0.73 nm and 3.72 ± 1.03 nm were observed for MLB, depending on the amount of excess Si in the SRO film. An enhanced photoluminescence (PL) emission (eight-fold more) was observed in MLA as compared to MLB due to the presence of the Si-NPs. Therefore, the influence of graded silicon content in SRN/SRO multilayer structures on the formation of Si-NPs and Si-ncs, and their relation to the PL emission, was analyzed.

Heteroepitaxial Growth of 3C-SiC on Si (111) Substrate Using AlN as a Buffer Layer

2008 ◽  
Vol 600-603 ◽  
pp. 251-254 ◽  
Author(s):  
Yong Mei Zhao ◽  
Guo Sheng Sun ◽  
Xing Fang Liu ◽  
Jia Ye Li ◽  
Wan Shun Zhao ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Chemical Vapor ◽  
Heteroepitaxial Growth ◽  
Si Substrate ◽  
Si Substrates ◽  
Good Crystallinity ◽  
Aln Film ◽  
Pressure Chemical ◽  
Aln Buffer ◽  
Sic Film

Using AlN as a buffer layer, 3C-SiC film has been grown on Si substrate by low pressure chemical vapor deposition (LPCVD). Firstly growth of AlN thin films on Si substrates under varied V/III ratios at 1100oC was investigated and the (002) preferred orientational growth with good crystallinity was obtained at the V/III ratio of 10000. Annealing at 1300oC indicated the surface morphology and crystallinity stability of AlN film. Secondly the 3C-SiC film was grown on Si substrate with AlN buffer layer. Compared to that without AlN buffer layer, the crystal quality of the 3C-SiC film was improved on the AlN/Si substrate, characterized by X-ray diffraction (XRD) and Raman measurements.

scholarly journals Research on the Preparation and Spectral Characteristics of Graphene/TMDs Hetero-structures

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Tao Han ◽  
Hongxia Liu ◽  
Shulong Wang ◽  
Shupeng Chen ◽  
Kun Yang
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Spectral Characteristics ◽  
Graphene Film ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Method ◽  
Si Substrate ◽  
Broadband Absorption ◽  
Gate Effect ◽  
Pressure Chemical

AbstractThe Van der Waals (vdWs) hetero-structures consist of two-dimensional materials have received extensive attention, which is due to its attractive electrical and optoelectronic properties. In this paper, the high-quality large-size graphene film was first prepared by the chemical vapor deposition (CVD) method; then, graphene film was transferred to SiO2/Si substrate; next, the graphene/WS2 and graphene/MoS2 hetero-structures were prepared by the atmospheric pressure chemical vapor deposition method, which can be achieved by directly growing WS2 and MoS2 material on graphene/SiO2/Si substrate. Finally, the test characterization of graphene/TMDs hetero-structures was performed by AFM, SEM, EDX, Raman and PL spectroscopy to obtain and grasp the morphology and luminescence laws. The test results show that graphene/TMDs vdWs hetero-structures have the very excellent film quality and spectral characteristics. There is the built-in electric field at the interface of graphene/TMDs heterojunction, which can lead to the effective separation of photo-generated electron–hole pairs. Monolayer WS2 and MoS2 material have the strong broadband absorption capabilities, the photo-generated electrons from WS2 can transfer to the underlying p-type graphene when graphene/WS2 hetero-structures material is exposed to the light, and the remaining holes can induced the light gate effect, which is contrast to the ordinary semiconductor photoconductors. The research on spectral characteristics of graphene/TMDs hetero-structures can pave the way for the application of novel optoelectronic devices.

Characterization of Polycrystalline Silicon Multilayers with thin Nitride/Oxide Films Using Spectroscopic Ellipsometry

1993 ◽  
Vol 324 ◽  
Author(s):  
L.M. Asinovsky
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Polycrystalline Silicon ◽  
Chemical Vapor ◽  
Strongly Correlated ◽  
Si Substrate ◽  
Lorentz Oscillator ◽  
Pressure Chemical ◽  
Complete Recrystallization ◽  
Nitride Oxide

AbstractSpectroscopic ellipsometry has been used to characterize oxide/poly-Si/oxide with thin nitride/oxide layer. Films were deposited on Si substrate using low-pressure chemical vapor deposition (LPCVD) techniques. The measurements were taken at angles of incidence of 65 and 70 degrees in the wavelength range from 300 to 800 nm. The analysis of the data using effective medium and two-dimensional Lorentz oscillator approximations identified complete recrystallization of the poly-Si after annealing and and its transformation to µ c-Si. Three wafers taken at the sequential stages of the manufacturing process were studied. Although parameters of the thin nitride/oxide layers are strongly correlated, reasonable estimates of the thicknesses were found. The resuilts were consistent with the measured Auger electron spectroscopy (AES) profiles.

scholarly journals Effect of Nucleation Parameters of Ge Quantum Dots Grown over Silicon Oxide by LPCVD

2007 ◽  
Vol 2 (2) ◽  
pp. 81-84
Author(s):  
S. N. M. Mestanza ◽  
I. Doi ◽  
N. C. Frateschi
Keyword(s):  
Quantum Dots ◽  
Silicon Oxide ◽  
Chemical Vapor ◽  
Force Microscopy ◽  
Nucleation Parameters ◽  
Atomic Force ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
Mean Size ◽  
Germanium Quantum Dots

Germanium quantum dots (Ge-QD) were grown by Low Pressure Chemical Vapor Deposition (LPCVD) on Si nucleus previously grown on 3 nm thick SiO2 ultra thin film. Samples were analyzed by atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). We report the analysis of the influence of the nucleation parameters on size and spatial distribution of Ge-QD. AFM images show a Ge-QD density of around 3.6x1010 cm-2, with an 11 nm mean size and 2.9 nm height. Finally, HRTEM investigation shows that the Ge-QD have a crystalline structure, i.e., they are nanocrystals.

Stress Effects on Nanocrystal Formation by Ni-Induced Crystallization of Amorphous Si

2003 ◽  
Vol 762 ◽  
Author(s):  
Yaocheng Liu ◽  
Michael D. Deal ◽  
Mahmooda Sultana ◽  
James D. Plummer
Keyword(s):  
Low Temperature ◽  
Integrated Circuits ◽  
Crystallization Rate ◽  
Chemical Vapor ◽  
Sputtering Deposition ◽  
Si Nanocrystals ◽  
Pressure Chemical ◽  
Amorphous Si ◽  
Si Films ◽  
Induced Crystallization

AbstractMetal-induced crystallization (MIC) of amorphous Si is gaining increased interest because of its potential use for low-temperature fabrication of integrated circuits. In this work, the MIC technique was used to make Si nanocrystals and the effects of stress on the crystallization were studied. Amorphous Si films were deposited onto the Si substrate with thermal oxides on top by low-pressure chemical vapor deposition (LPCVD) and then patterned into nanoscale pillars by electron beam lithography and reactive ion etching. A conformal low-temperature oxide (LTO) layer was deposited to cover the pillars, followed by an anisotropic etch back to form a spacer, leaving only the top surface of the pillars exposed to the 5 nm Ni sputtering deposition afterwards. An HF dip was used to partially remove the LTO spacers on the pillars, leading to different LTO thicknesses on different samples. These samples were then annealed to crystallize the amorphous Si pillars, forming Si nanocrystals. Transmission electron microscope (TEM) observations after anneal found a clear dependence of the crystallization rate on the pillar size as well as the LTO thickness. The crystallization rate was lower for pillars with thicker LTO spacers, while for the same LTO thickness the crystallization rate was lower for pillars with narrower width. A model based on the stress in the pillars is proposed to explain this dependence. This model suggests some methods to control the nickel-induced crystallization process and achieve higher quality Si nanocrystals.

Tailored Deposition by LPCVD of Non-stoichiometric Si Oxides and their Application in the Formation of Si Nanocrystals Embedded in SiO2 by Thermal Annealing

2007 ◽  
Vol 989 ◽  
Author(s):  
Bruno Morana ◽  
Juan Carlos G. de Sande ◽  
Andrés Rodríguez ◽  
Jesús Sangrador ◽  
Tomás Rodríguez ◽  
...  
Keyword(s):  
Growth Rate ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Silicon Oxide ◽  
Chemical Vapor ◽  
Design Experiment ◽  
Si Nanocrystals ◽  
Pressure Chemical ◽  
Face Centered ◽  
Central Composite

AbstractSilicon oxide films with excess of Si were deposited by Low Pressure Chemical Vapor Deposition. The growth rate of the films and the excess of silicon in them have been modeled using a Face-centered Central Composite Design experiment. Samples annealed at 1100°C show luminescence (665 nm) at 80K and at room temperature associated to Si nanocrystals.

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