Injection Electroluminescence from Thin Film p-i-n Structures made from Nanocrystalline Hydrogenated Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
A. A. Andreev ◽  
B. Y. Averbouch ◽  
P. Mavlyanov ◽  
S. B. Aldabergenova ◽  
M. Albrecht ◽  
...  
Keyword(s):  
Amorphous Matrix ◽  
Volume Fraction ◽  
Interband Transition ◽  
Stokes Shift ◽  
Chemical Vapour ◽  
Nanocrystalline Silicon ◽  
Film Structure ◽  
High Hydrogen ◽  
Fast Kinetics ◽  
Deposition Parameter

AbstractNanocrystalline silicon films are prepared by plasma enhanced chemical vapour deposition of silane under the conditions of high hydrogen dilution (3:100). The film structure consists of nanoclusters 0.8 to 5 nm in size (volume fraction 30%) embedded in an amorphous matrix. The Taue gap of the amorphous matrix is 1.95 to 2.05 eV depending on deposition parameter. These films are characterized as regards photoluminescence (PL) and, prepared to p-i-n structures, electroluminescence (EL). The PL and EL agree in (i) luminescence peak at 1.9 eV, i.e. small Stokes shift, (ii) almost no temperature dependence between 77 K and 293 K, (iii) fast kinetics with time constant of a few 10−8 s. These data can be understood in terms of quantum confinement in Si nanocrystallites smaller than around 2 nm. The EL in addition exhibits a luminescence band extending up to 3 eV, which can be interpreted by interband transition due the hot carriers.

Stress and Crystallization of Plasma Enhanced Chemical Vapour Deposition Nanocrystalline Silicon Films

2008 ◽  
Vol 8 (5) ◽  
pp. 2693-2698 ◽  
Author(s):  
S. B. Milne ◽  
Y. Q. Fu ◽  
J. K. Luo ◽  
A. J. Flewitt ◽  
S. Pisana ◽  
...  
Keyword(s):  
Film Growth ◽  
Chemical Vapour ◽  
Nanocrystalline Silicon ◽  
Film Structure ◽  
Intrinsic Stress ◽  
Plasma Power ◽  
Annealing Conditions ◽  
Si Films ◽  
Gas Ratio ◽  
Nanocrystalline Si

Nanocrystalline Si films were prepared with a RF-PECVD system using different SiH4/H2 ratios, plasma powers, substrate temperatures and annealing conditions. The film's intrinsic stress was characterized in relation to the crystallization fraction. Results show that an increasing H2 gas ratio, plasma power or substrate temperature can shift the growth mechanism across a transition point, past which nanocrystalline Si is dominant in the film structure. The film's intrinsic stress normally peaks during this transition region. Different mechanisms of stress formation and relaxation during film growth were discussed, including ion bombardment effects, hydrogen induced bond-reconstruction and nanocomposite effects (nanocrystals embedded in an amorphous Si matrix). A three-parameter schematic plot has been proposed which is based on the results obtained. The film structure and stress are presented in relation to SiH4 gas ratio, plasma power and temperature.

Microcrystalline and Nanocrystalline Silicon: Simulation of Material Properties

2005 ◽  
Vol 862 ◽  
Author(s):  
R. Biswas ◽  
B. C. Pan ◽  
V. Selvaraj
Keyword(s):  
Silicon Nanowires ◽  
Amorphous Matrix ◽  
Volume Fraction ◽  
Crystalline Silicon ◽  
Amorphous Region ◽  
Nanocrystalline Silicon ◽  
Nano Crystalline ◽  
Crystalline Core ◽  
Silicon Structures ◽  
Dynamics Simulations

AbstractWe have simulated nano-crystalline silicon and microcrystalline silicon structures with varying crystallite volume fractions, using molecular dynamics simulations. The crystallite regions reside in an amorphous matrix. We find the amorphous matrix is better ordered in nanocrystalline-Si than in the homogenous amorphous silicon networks, consistent with the observed higher stability of H-diluted films. There is a critical size above which the crystallites are stable and may grow. Sub-nm size crystallites in the protocrystalline phase are found to reduce the strain of the amorphous matrix. We simulated micro-crystalline silicon with a substantial crystallite volume fraction. Microcrystalline structures exhibit a crystalline core surrounded by an amorphous shell with similarities to silicon nanowires. We find a relatively uniform H distribution in the amorphous region and a crystal-amorphous phase boundary that is not welldefined.

Boron-Doped Nanocrystalline Silicon Thin Films Prepared by PECVD

2012 ◽  
Vol 503 ◽  
pp. 386-390
Author(s):  
Xiu Qin Wang ◽  
Jian Ning Ding ◽  
Ning Yi Yuan ◽  
Shu Bo Wang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Substrate Temperature ◽  
Volume Fraction ◽  
Chemical Vapour ◽  
Nanocrystalline Silicon ◽  
Process Conditions ◽  
Rf Power ◽  
Silicon Thin Films ◽  
Boron Doped

Boron-doped nanocrystalline silicon thin films(p-nc-Si:H) were deposited on glass substrates by plasma enhanced chemical vapour deposition (PECVD) using SiH4/ H2/ B2H6. The effects of substrate temperature, rf power and diborane flow on the microstructure, the electrical properties of nanocrystalline silicon thin films have been investigated. The results show that, increasing substrate temperature, rf power and B2H6flow can improve the conductivity of P-Si thin film. However, exceeding one value, they are not advantageous to improve the conductivity due to the decrystallization of films. Hence, appropriate process conditions are crucial for the preparation of high quality p layer. crystalline volume fraction (Xc) 26.2 %, mean grain size (d) 3.5nm and conductivity 0.374S/cm, p-nc-Si:H thin film was deposited.

Oxidation Reduction in Nanocrystalline Silicon Grown by Hydrogen-Profiling Technique

2016 ◽  
Vol 41 ◽  
pp. 9-17 ◽  
Author(s):  
Christopher J. Arendse ◽  
Theophillus F.G. Muller ◽  
Franscious R. Cummings ◽  
Clive J. Oliphant
Keyword(s):  
Amorphous Silicon ◽  
Hydrogen Concentration ◽  
Film Growth ◽  
Volume Fraction ◽  
Crystalline Silicon ◽  
Chemical Vapour ◽  
Silicon Layer ◽  
Nanocrystalline Silicon ◽  
Substrate Interface ◽  
Nano Crystalline

The deposition of a compact amorphous silicon/nano-crystalline silicon material is demonstrated by hot-wire chemical vapour deposition using a sequential hydrogen profiling technique at low hydrogen dilutions. Nano-crystallite nucleation occurs at the substrate interface that develops into a uniform, porous crystalline structure as the growth progresses. A further reduction in the H-dilution results in the onset of a dense amorphous silicon layer. The average crystalline volume fraction and nano-crystallite size in the sample bulk amounts to 30% and 6 nm, respectively, as probed by Raman spectroscopy using the 647 nm excitation. The change in hydrogen dilution is accompanied by a graded hydrogen concentration depth-profile, where the hydrogen concentration decreases as the growth progresses. The level of post-deposition oxidation is considerably reduced, as inferred from infrared spectroscopy. The presence of oxygen is mainly confined to the substrate interface as a result of thermal oxidation during thin film growth.

Investigation of the Amorphous to Nanocrystalline Phase Transition at the Deposition of Silicon Films in an ECWR Plasma of Pure SiH4

1996 ◽  
Vol 420 ◽  
Author(s):  
M. Scheib ◽  
B. Schrcder ◽  
H. Oechsner
Keyword(s):  
Phase Transition ◽  
Chemical Vapour ◽  
Optical Emission ◽  
Nanocrystalline Silicon ◽  
Nanocrystalline Phase ◽  
Plasma Parameters ◽  
Deposition Rates ◽  
High Hydrogen ◽  
Hydrogen Dilution ◽  
Wave Resonance

AbstractA novel plasma based chemical vapour deposition (PECVD) technique employing electron cyclotron wave resonance (ECWR) for plasma excitation was applied to the deposition of hydrogenated nanocrystalline silicon (nc-Si:H) films. nc-Si:H films were produced at deposition rates up to 8Å/sec (TS = 200°C) with a pure SiH4 plasma in contrast to the conventional glow discharge technique where the high hydrogen dilution usually needed leads to considerable lower deposition rates. The amorphous-to-nanocrystalline phase transition was investigated in dependence of substrate temperature, the hf-power and magnetic field mandatory for ECWR, and SiH4-flow into the plasma. With the knowledge of the plasma parameters derived from single probe measurements, and the intensities of excited plasma species detected by means of optical emission spectroscopy we can qualitatively describe the silane-plasma dissociation behaviour. The nanocrystalline phase is found to be always deposited when the dissociation degree of the SiH4 plasma is almost saturated.

Structural and Electronic Properties of Hydrogenated Nanocrystalline Silicon Films Made with Hydrogen Dilution Profiling Technique

2005 ◽  
Vol 862 ◽  
Author(s):  
Keda Wang ◽  
Daxing Han ◽  
D. L. Williamson ◽  
Brittany Huie ◽  
J. R. Weinberg-Wolf ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Volume Fraction ◽  
Nanocrystalline Silicon ◽  
Growth Direction ◽  
Structure Evolution ◽  
Excitation Wavelength ◽  
Initial Growth ◽  
High Hydrogen ◽  
Hydrogen Dilution ◽  
Structural And Electronic Properties

AbstractWe used X-ray diffraction (XRD), Raman scattering and photoluminescence (PL) spectroscopy to characterize structural and electronic properties of nc-Si:H films made with different hydrogen dilution ratios and hydrogen dilution profiling with continuously reduced hydrogen dilution during the deposition. The XRD results show that the crystalline volume fraction (fc) is in the range of 60-70% with grain size of 22-26 nm for the nc-Si:H films studied. Comparing the sample made using hydrogen dilution profiling to that with constant hydrogen dilution, the hydrogen dilution profiling promotes the (220) preferential orientation due to a very high hydrogen dilution in the initial growth. The Raman results show that the fc is in the range of 60-90%, depending on the sample and excitation wavelength. For the samples with constant hydrogen dilution, the fc measured by Raman increases along the growth direction. The hydrogen dilution profiling reverses this trend, which affirms that the hydrogen profiling controls the nanocrystalline structure evolution along the growth direction. The PL results show only one peak around 0.8-0.9 eV for the samples made with constant hydrogen dilution, but an additional peak at 1.4 eV appears in the sample made with the hydrogen dilution profiling.

Nanocrystalline silicon ( nc-Si ) from single ion beam sputtering

2003 ◽  
Vol 762 ◽  
Author(s):  
Z.B. Zhou ◽  
G.M. Hadi ◽  
R.Q. Cui ◽  
Z.M. Ding ◽  
G. Li
Keyword(s):  
Solar Cell ◽  
Ion Beam ◽  
Nanocrystalline Silicon ◽  
Silicon Films ◽  
Chamber Pressure ◽  
Ion Beam Sputtering ◽  
High Hydrogen ◽  
Beam Sputtering ◽  
Si Films ◽  
Nanocrystalline Silicon Films

AbstractBased on a small set of selected publications on the using of nanocrystalline silicon films (nc-Si) for solar cell from 1997 to 2001, this paper reviews the application of nc-Si films as intrinsic layers in p-i-n solar cells. The new structure of nc-Si films deposited at high chamber pressure and high hydrogen dilution have characters of nanocrystalline grains with dimension about several tens of nanometer embedded in matrix of amorphous tissue and a high volume fraction of crystallinity (60~80%). The new nc-Si material have optical gap of 1.89 eV. The efficiency of this single junction solar cell reaches 8.7%. This nc-Si layer can be used not only as an intrinsic layer and as a p-type layer. Also nanocrystalline layer may be used as a seed layer for the growth of polycrystalline Si films at a low temperature.We used single ion beam sputtering methods to synthesize nanocrystalline silicon films successfully. The films were characterized with the technique of X-ray diffraction, Atomic Force Micrographs. We found that the films had a character of nc-amorphous double phase structure. Conductivity test at different temperatures presented the transportation of electrons dominated by different mechanism within different temperature ranges. Photoconductivity gains of the material were obtained in our recent investigation.

Amorphous-to-nanocrystalline transition in silicon thin films by hydrogen diluted silane using PE-CVD method

2020 ◽  
Vol 13 ◽  
Author(s):  
Ashok Jadhavar ◽  
Vidya Doiphode ◽  
Ajinkya Bhorde ◽  
Yogesh Hase ◽  
Pratibha Shinde ◽  
...  
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Defect Density ◽  
Hydrogen Flow Rate ◽  
Spectroscopy Analysis ◽  
Deposition Parameter ◽  
Hydrogen Flow ◽  
Cvd Method ◽  
Silicon Thin Films ◽  
Increasing Trend

: Herein, we report effect of variation of hydrogen flow rate on properties of Si:H films synthesized using PE-CVD method. Raman spectroscopy analysis show increase in crystalline volume fraction and crystallite size implying that hydrogen flow in PECVD promote the growth of crystallinity in nc-Si:H films with an expense of reduction in deposition rate. FTIR spectroscopy analysis indicates that hydrogen content in the film increases with increase in hydrogen flow rate and hydrogen is predominantly incorporated in Si-H2 and (Si-H2)n bonding configuration. The optical band gap determined using E04 method and Tauc method (ETauc) show increasing trend with increase in hydrogen flow rate and E04 is found higher than ETauc over the entire range of hydrogen flow rate studied. We also found that the defect density and Urbach energy also increases with increase in hydrogen flow rate. Photosensitivity (Photo /Dark) decreases from  103 to  1 when hydrogen flow rate increased from 30 sccm to 100 sccm and can attributed to amorphous-to-nanocrystallization transition in Si:H films. The results obtained from the present study demonstrated that hydrogen flow rate is an important deposition parameter in PE-CVD to synthesize nc-Si:H films.

Hydrogen-induced amorphization and embrittlement resistance in Ti-based in situ composite with bcc-phase in an amorphous matrix

2007 ◽  
Vol 22 (2) ◽  
pp. 428-436 ◽  
Author(s):  
S. Jayalakshmi ◽  
J.P. Ahn ◽  
K.B. Kim ◽  
E. Fleury
Keyword(s):  
Hydrogen Embrittlement ◽  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
Mechanical Tests ◽  
High Concentration ◽  
High Hydrogen ◽  
In Situ Composite ◽  
Bcc Phase ◽  
Embrittlement Resistance

We report the hydrogenation characteristics and mechanical properties of Ti50Zr25Cu25 in situ composite ribbons, composed of β-Ti crystalline phase dispersed in an amorphous matrix. Upon cathodic charging at room temperature, high hydrogen absorption up to ∼60 at.% (H/M = ∼1.2) is obtained. At such a high concentration, hydrogen-induced amorphization occurs. Mechanical tests conducted on the composite with varying hydrogen concentrations indicate that the Ti50Zr25Cu25 alloy is significantly resistant to hydrogen embrittlement when compared to conventional amorphous alloys. A possible mechanism that would contribute toward hydrogen-induced amorphization and hydrogen embrittlement is discussed.

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