Large Red Shift of PL Peak Energy in High Growth Rate a-Si:H Prepared by Hot-Wire CVD

2001 ◽  
Vol 664 ◽  
Author(s):  
Daxing Han ◽  
Guozhen Yue ◽  
Jennifer Weinberg-Wolf ◽  
Jessica M. Owens ◽  
Yueqin Xu ◽  
...  
Keyword(s):  
Growth Rate ◽  
Electronic States ◽  
High Growth ◽  
High Growth Rate ◽  
Red Shift ◽  
Hot Wire ◽  
Nano Scale ◽  
Peak Energy ◽  
Order Of Magnitude ◽  
Standard Rate

ABSTRACTWe characterized the electronic states and microstructure of high-growth-rate a-Si:H films by employing photoluminescence (PL) and Raman spectroscopies. The growth rate was from 50 to 115 Å/s compared to the standard rate of less than 10 Å/s. For the high-growth-rate a-Si:H films, we observed typical a-Si:H features in Raman but new features in PL. The new PL features are: a) the PL peak energy is as low as ∼1.15 eV compared to the standard ∼1.4 eV at 80 K; and b) the total intensity is more than one order of magnitude higher then the standard. We suggest that the nano-scale microstructure may be responsible for the anomalous PL features.

Guiding Principle to Develop Intrinsic Microcrystalline Silicon Absorber Layer For Solar Cell By Hot-Wire Cvd

2001 ◽  
Vol 664 ◽  
Author(s):  
A. R. Middya ◽  
U. Weber ◽  
C. Mukherjee ◽  
B. Schroeder
Keyword(s):  
Growth Rate ◽  
Solar Cell ◽  
Cell Structure ◽  
Short Circuit ◽  
Chemical Vapor ◽  
High Growth ◽  
High Growth Rate ◽  
Open Circuit ◽  
Hot Wire ◽  
Microcrystalline Silicon

ABSTRACTWe report on ways to develop device quality microcrystalline silicon (μc-Si:H) intrinsic layer with high growth rate by hot-wire chemical vapor deposition (HWCVD). With combine approach of controlling impurities and moderate H-dilution [H2/SiH4 ͌ 2.5], we developed, for the first time, highly photosensitive (103 μc-Si:Hfilms with high growth rate (>1 nm/s); the microstructure of the film is found to be close to amorphous phase (fc ͌ 46 ̻± 5%). The photosensitivity systematically decreases with fc and saturates to 10 for fc> 70%. On application of these materials in non-optimized pin [.proportional]c-Si:H solar cell structure yields 700 mV open-circuit voltage however, surprisingly low fill factor and short circuit current. The importance of reduction of oxygen impurities [O], adequate passivation of grain boundary (GB) as well as presence of inactive GB of (220) orientation to achieve efficient [.proportional]c-Si:H solar cells are discussed.

Microstructure and mechanical property of high growth rate SiC via continuous hot‐wire CVD

2019 ◽  
Vol 102 (9) ◽  
pp. 5656-5667 ◽  
Author(s):  
Shuai Liu ◽  
Yanqing Yang ◽  
Xian Luo ◽  
Bin Huang ◽  
Na Jin ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Hot Wire ◽  
Microstructure And Mechanical Property

scholarly journals Concentrated Chloride-Based Epitaxial Growth of 4H-SiC

2010 ◽  
Vol 645-648 ◽  
pp. 95-98 ◽  
Author(s):  
Anne Henry ◽  
Stefano Leone ◽  
Sven Andersson ◽  
Olof Kordina ◽  
Erik Janzén
Keyword(s):  
Growth Rate ◽  
Epitaxial Growth ◽  
Systematic Study ◽  
High Growth ◽  
Growth Conditions ◽  
High Growth Rate ◽  
Gas Mixture ◽  
Process Pressure ◽  
Order Of Magnitude ◽  
Standard Gas

A chloride-based CVD process has been studied in concentrated growth conditions. A systematic study of different carrier flows and pressures has been done in order to get good quality epilayers on 8° off and on-axis substrates while using very low carrier flows. Hydrogen chloride (HCl) was added to the standard gas mixture to keep a high growth rate and to get homo-polytypic growth on on-axis substrates. The carrier flow was reduced down to one order of magnitude less than under typical growth condition. By lowering the process pressure it was possible to reduce precursor depletion along the susceptor which improved the thickness uniformity to below 2% variation (σ/mean) over a 2” diameter wafer.

Process Parameters for Poly-Silicon Deposition at a High Growth Rate (1-7 nm/s) by Hot-Wire Chemical Vapour Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
J.K. Rath ◽  
A.J. Hardeman ◽  
C.H.M. van der Werf ◽  
P.A.T.T. van Veenendaal ◽  
M.Y.S. Rusche ◽  
...  
Keyword(s):  
Growth Rate ◽  
Chemical Vapour Deposition ◽  
Process Parameters ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
High Growth ◽  
High Growth Rate ◽  
Hot Wire ◽  
High Hydrogen ◽  
Si Films

AbstractHigh silane to hydrogen flow ratios and optimum wire temperatures are the key process parameters to achieve high growth rate poly-silicon films by hot wire chemical vapour deposition (HWCVD) using a four-wire hot-wire assembly. Four tungsten wires, 4 cm apart from each other, were used as catalytic filaments. Growth rates higher than 7 nm/s have been achieved at a substrate temperature of ∼510°C. The increase in deposition rate was accompanied by deterioration of two physical properties i.e., decrease in photoresponse and increase in oxygen incorporation in the film, which is attributed to high porosity in the material that is commonly observed in these high growth rate materials. The process conditions to incorporate a high hydrogen content into the material for passivation of defects and donor states have been identified as high hydrogen dilution and lower wire temperature. With these procedures, poly-Si films deposited at 1.3 nm/s showed a high ambipolar diffusion length of 132 nm. Incorporating such poly-Si films as the i-layer in an n-i-p solar cell on a stainless steel substrate, without back reflector, showed an efficiency of 4.4 % and a high open circuit voltage of 0.58 V, which is attributed to effective passivation of defects and dopants by incorporated hydrogen.

High Growth Rate with Reduced Surface Roughness during On-Axis Homoepitaxial Growth of 4H-SiC

2011 ◽  
Vol 679-680 ◽  
pp. 115-118 ◽  
Author(s):  
Jawad ul Hassan ◽  
Peder Bergman ◽  
Anne Henry ◽  
Erik Janzén
Keyword(s):  
Growth Rate ◽  
Surface Roughness ◽  
Surface Morphology ◽  
High Growth ◽  
Lower Surface ◽  
Growth Conditions ◽  
High Growth Rate ◽  
Homoepitaxial Growth ◽  
Order Of Magnitude ◽  
Reduced Surface

The effect of different C/Si ratio on the surface morphology has been studied to optimize the on-axis homoepitaxial growth conditions on 4H-SiC substrates to improve the surface roughness of epilayers. The overall surface roughness is found to decrease with decreasing C/Si ratio. An order of magnitude lower surface roughness has been observed using C/Si ratio = 0.8 without disturbing the polytype stability in the epilayer. A high growth rate of 10 µm/h was achieved without introducing 3C inclusions. The epilayers grown at higher growth rate with C/Si ratio = 1 also had improvements in the surface roughness. 100% 4H polytype was maintained in the epilayers grown with C/Si ratio in the range of 1.2 to 0.8 and with high growth rate of 10 µm/h.

Exploring SiC Growth Limitation of Vapor-Liquid-Solid Mechanism when Using Two Different Carbon Precursors

2013 ◽  
Vol 740-742 ◽  
pp. 323-326
Author(s):  
Kassem Alassaad ◽  
François Cauwet ◽  
Davy Carole ◽  
Véronique Soulière ◽  
Gabriel Ferro
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Carbon Precursor ◽  
Growth Limitation ◽  
Vapor Liquid Solid ◽  
Partial Pressures ◽  
Vapor Liquid Solid Mechanism ◽  
Vls Growth ◽  
Vapor Liquid

Abstract. In this paper, conditions for obtaining high growth rate during epitaxial growth of SiC by vapor-liquid-solid mechanism are investigated. The alloys studied were Ge-Si, Al-Si and Al-Ge-Si with various compositions. Temperature was varied between 1100 and 1300°C and the carbon precursor was either propane or methane. The variation of layers thickness was studied at low and high precursor partial pressure. It was found that growth rates obtained with both methane and propane are rather similar at low precursor partial pressures. However, when using Ge based melts, the use of high propane flux leads to the formation of a SiC crust on top of the liquid, which limits the growth by VLS. But when methane is used, even at extremely high flux (up to 100 sccm), no crust could be detected on top of the liquid while the deposit thickness was still rather small (between 1.12 μm and 1.30 μm). When using Al-Si alloys, no crust was also observed under 100 sccm methane but the thickness was as high as 11.5 µm after 30 min growth. It is proposed that the upper limitation of VLS growth rate depends mainly on C solubility of the liquid phase.

Very High Growth Rate of 4H-SiC Using MTS as Chloride-Based Precursor

2008 ◽  
Vol 600-603 ◽  
pp. 115-118 ◽  
Author(s):  
Henrik Pedersen ◽  
Stefano Leone ◽  
Anne Henry ◽  
Franziska Christine Beyer ◽  
Vanya Darakchieva ◽  
...  
Keyword(s):  
Growth Rate ◽  
Linear Dependence ◽  
Growth Rates ◽  
Molar Fraction ◽  
High Growth ◽  
High Growth Rate ◽  
Epitaxial Layers ◽  
Single Precursor ◽  
Very High

The chlorinated precursor methyltrichlorosilane (MTS), CH3SiCl3, has been used to grow epitaxial layers of 4H-SiC in a hot wall CVD reactor, with growth rates as high as 170 µm/h at 1600°C. Since MTS contains both silicon and carbon, with the C/Si ratio 1, MTS was used both as single precursor and mixed with silane or ethylene to study the effect of the C/Si and Cl/Si ratios on growth rate and doping of the epitaxial layers. When using only MTS as precursor, the growth rate showed a linear dependence on the MTS molar fraction in the reactor up to about 100 µm/h. The growth rate dropped for C/Si < 1 but was constant for C/Si > 1. Further, the growth rate decreased with lower Cl/Si ratio.

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