scholarly journals On the Effect of Substrate Temperature on a-Si:H Deposition Using an Expanding Thermal Plasma

1996 ◽  
Vol 420 ◽  
Author(s):  
R. J. Severens ◽  
M. C. M. Van De Sanden ◽  
H. J. M. Verhoeven ◽  
J. Bastiaanssen ◽  
D. C. Schram
Keyword(s):  
Growth Rate ◽  
Substrate Temperature ◽  
Urbach Energy ◽  
Hydrogen Plasma ◽  
Hydrogen Abstraction ◽  
Plasma Jet ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Simple Kinetic Model ◽  
S Deposition

AbstractFast (7 nm/s) deposition of amorphous hydrogenated silicon with a midgap density of states less than 1016 cm-3 and an Urbach energy of 50 meV has been achieved using a remote argon/hydrogen plasma. The plasma is generated in a dc thermal arc (0.5 bar, 5 kW) and expands into a low pressure chamber (20 Pa) thus creating a plasma jet with a typical flow velocity of 103 m/s. Pure silane is injected into the jet immediately after the nozzle, in a typical flow mixture of Ar:H2:SiH4=55:10:10 scc/s. As the electron temperature in the recombining plasma is low (typ. 0.3 eV), silane radicals are thought to be produced mainly by hydrogen abstraction.Material quality in terms of refractive index, conductivity, microstructure parameter and optical bandgap was found to increase monotonously with substrate temperature, even up to 350 °C; for practically all low growth rate deposition schemes an optimum around 250 °C is observed. It will be argued that this behavior is consistent with a simple kinetic model involving physisorption and hopping, growth on dangling bonds and thermal desorption of hydrogen.

An Expanding Thermal Plasma for Deposition of a-Si:H

1995 ◽  
Vol 377 ◽  
Author(s):  
R. J. Severens ◽  
G. J. H. Brussaard ◽  
H. J. M. Verhoeven ◽  
M. C. M. Van de Sanden ◽  
D. C. Schram
Keyword(s):  
Hydrogen Content ◽  
Hydrogen Plasma ◽  
Hydrogen Abstraction ◽  
Dissociative Recombination ◽  
Operating Conditions ◽  
Refractive Indices ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
20 Nm

ABSTRACTA remote argon/hydrogen plasma is used to deposit amorphous hydrogenated silicon. The plasma is generated in a DC thermal arc (typical operating conditions 0.5 bar, 5 kW) and expands into a low pressure chamber (20 Pa) thus creating a plasma jet with a typical flow velocity of 103 m/s. Pure silane is injected into the jet immediately after the nozzle, in a typical flow mixture of Ar:H2:SiH4=55:10:6 scc/s. The electron temperature in the jet is low (typ. 0.3 eV) : silane radicals are thought to be produced mainly by hydrogen abstraction, but also by a sequence of dissociative charge exchange and consecutive dissociative recombination. In-situ ellipsometry yields refractive indices of 3.6–4.2 at 632.8 nm and growth rates of 10–20 nm/s. FTIR analysis yields a hydrogen content of 9–25 at.% and refractive indices of 2.7–3.3 in the infrared. The SiH density decreases with increasing hydrogen content, whereas the SiH2 density increases. Above 11 at.%, the majority of hydrogen is bonded in the SiH2 configuration. The optical bandgap remains constant at approximately 1.72 eV. The photoconductivity is of the order 101–6 (Ωcm) 1–6 and the photoresponse 106.

Effect of the Substrate Temperature on the Transition from Amorphous to Microcrystalline Silicon with High Hydrogen Dilution

2013 ◽  
Vol 773 ◽  
pp. 520-523
Author(s):  
Ming Liang Zhang ◽  
Hui Dong Yang ◽  
Kai Zhao Yang
Keyword(s):  
Substrate Temperature ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Silicon Films ◽  
Microcrystalline Silicon ◽  
High Hydrogen ◽  
Hydrogenated Silicon ◽  
Glass Substrates ◽  
Amorphous Hydrogenated Silicon ◽  
The Stability

Transition films of amorphous hydrogenated silicon (a-Si:H) to microcrystalline silicon (μc-Si:H) have attracted much attention due to the stability, high overall quality for solar cells configuration. Hydrogenated amorphous and microcrystalline silicon films were deposited on glass substrates by a conventional plasma enhanced chemical vapor deposition (PEVCD) varying the substrate temperature from 275 to 350 °C. A silane concentration of 4% and a total flow rate of 100 sccm were used at a gas pressure of 267 Pa. The film thicknesses of the prepared samples were between 700 and 900 nm estimated from the optical transmission spectra. The deposition rates were between 0.2 and 0.3 nm/s. The phase composition of the deposited silicon films were investigated by Raman spectroscopy. The transition from amorphous to microcrystalline silicon was found at the higher temperatures. The crystallization process of the amorphous silicon can be affected by the substrate temperature. A narrow structural transition region was observed from the changes of the crystalline volume fraction. The dark electrical conductivity of the silicon films increased as the substrate temperature increasing.

Bandgap Engineering of Amorphous Hydrogenated Silicon Carbide

MRS Advances ◽  
2016 ◽  
Vol 1 (43) ◽  
pp. 2929-2934 ◽  
Author(s):  
J. A. Guerra ◽  
L. M. Montañez ◽  
K. Tucto ◽  
J. Angulo ◽  
J. A. Töfflinger ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Urbach Energy ◽  
Amorphous Material ◽  
Deposition Process ◽  
Bandgap Energy ◽  
Bandgap Engineering ◽  
Hydrogenated Silicon ◽  
Hydrogen Dilution ◽  
Amorphous Hydrogenated Silicon ◽  
Proposed Model

ABSTRACTA simple model to describe the fundamental absorption of amorphous hydrogenated silicon carbide thin films based on band fluctuations is presented. It provides a general equation describing both the Urbach and Tauc regions in the absorption spectrum. In principle, our model is applicable to any amorphous material and it allows the determination of the bandgap. Here we focus on the bandgap engineering of amorphous hydrogenated silicon carbide layers. Emphasis is given on the role of hydrogen dilution during the deposition process and post deposition annealing treatments. Using the conventional Urbach and Tauc equations, it was found that an increase/decrease of the Urbach energy produces a shrink/enhancement of the Tauc-gap. On the contrary, the here proposed model provides a bandgap energy which behaves independently of the Urbach energy.

Efficient Visible Room Temperature Photoluminescence in Wide Gap Hydrogenated Amorphous Silicon-Carbon Alloys

1994 ◽  
Vol 336 ◽  
Author(s):  
Leandro R. Tessler ◽  
Ionel Solomon
Keyword(s):  
Room Temperature ◽  
Urbach Energy ◽  
Photoluminescence Intensity ◽  
Tetrahedral Coordination ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Silicon Carbon ◽  
Hydrogenated Amorphous ◽  
Carbon Concentrations ◽  
Phonon Model

ABSTRACTWe report a photoluminescence study on amorphous hydrogenated silicon carbon (a-Si1-xCx:H) alloys with carbon concentration in the range O < x < 0.5, prepared by PECVD in the “low-power” regime, that preserves the tetrahedral coordination of the carbon atoms. These samples have optical gaps higher than conventional “high power” alloys with the same carbon content. For carbon concentrations below x = 0.2 the photoluminescence behaves essentially as in pure a-Si:H with increased gap, Urbach energy and DOS. For higher carbon concentrations there is a change in the recombination process, that we attribute to a change in the dominating diffusion process of the photogenerated carriers. The integrated photoluminescence intensity for carbon-rich samples is very weakly dependent on the temperature, and at room temperature it approaches that of pure a-Si:H at 77K. For all samples, the photoluminescence bandwidth can be well described by a zero-phonon model.

Deposition of Amorphous Hydrogenated Silicon Films by VUV Laser CVD: Influence of Substrate Temperature

1995 ◽  
Vol 377 ◽  
Author(s):  
H. Karstens ◽  
P. Hess
Keyword(s):  
Substrate Temperature ◽  
Dark Conductivity ◽  
Band Gap Energy ◽  
Poor Quality ◽  
Buffer Gas ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Influence Of Substrate ◽  
Parallel Configuration ◽  
Laser Cvd

ABSTRACTAmorphous hydrogenated silicon (a-Si:H) films were deposited from disilane at substrate temperatures between 180 and 390 °C using a F2-laser (157 nm) in a parallel configuration. Material properties such as hydrogen content, SiH and SiH2 group concentration, photo-and dark conductivity, band-gap energy and the Urbach parameter were determined as a function of the deposition temperature. The material with the best optical and electronical properties was found for a substrate temperature of 260 °C. Using argon as the buffer gas instead of helium results in films of poor quality.

Light-induced Stability of Layered Amorphous Hydrogenated Silicon Grown with Alternating Substrate Temperature

1996 ◽  
Vol 420 ◽  
Author(s):  
Jong-Hwan Yoona ◽  
Czang-Ho Lee
Keyword(s):  
Substrate Temperature ◽  
Defect Density ◽  
Single Layer ◽  
Light Illumination ◽  
Hydrogenated Silicon ◽  
Layer Film ◽  
Amorphous Hydrogenated Silicon ◽  
Improved Stability ◽  
Single Layer Film ◽  
Hydrogenated Amorphous

AbstractWe present the results of studies on the light-induced stability of undoped layered hydrogenated amorphous silicon films grown with alternating substrate temperature between optimal and non optimal temperatures for device-quality films. Compared to the single layer films grown at optimal substrate temperature, the layered films show improved stability in the lightinduced state. Under intense light illumination of 3 W/cm2, the steady-state defect density of the layered film reached a saturation of 2×1016 cm−3, while the single layer film saturates at about 6×1016 cm−3. It is found that in the completely degraded state the photoconductivity in the layered film is also improved by a factor of two compared to the single layer film.

scholarly journals Properties and Mechanism of PEALD-In2O3 Thin Films Prepared by Different Precursor Reaction Energy

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 978
Author(s):  
Ming-Jie Zhao ◽  
Zhi-Xuan Zhang ◽  
Chia-Hsun Hsu ◽  
Xiao-Ying Zhang ◽  
Wan-Yu Wu ◽  
...  
Keyword(s):  
Growth Rate ◽  
Substrate Temperature ◽  
Film Growth ◽  
Atomic Layer ◽  
Amorphous Structure ◽  
Reaction Energy ◽  
Film Growth Rate ◽  
In2o3 Film ◽  
Intermediate Temperature Range ◽  
Layer Deposition

Indium oxide (In2O3) film has excellent optical and electrical properties, which makes it useful for a multitude of applications. The preparation of In2O3 film via atomic layer deposition (ALD) method remains an issue as most of the available In-precursors are inactive and thermally unstable. In this work, In2O3 film was prepared by ALD using a remote O2 plasma as oxidant, which provides highly reactive oxygen radicals, and hence significantly enhancing the film growth. The substrate temperature that determines the adsorption state on the substrate and reaction energy of the precursor was investigated. At low substrate temperature (100–150 °C), the ratio of chemically adsorbed precursors is low, leading to a low growth rate and amorphous structure of the films. An amorphous-to-crystalline transition was observed at 150–200 °C. An ALD window with self-limiting reaction and a reasonable film growth rate was observed in the intermediate temperature range of 225–275 °C. At high substrate temperature (300–350 °C), the film growth rate further increases due to the decomposition of the precursors. The resulting film exhibits a rough surface which consists of coarse grains and obvious grain boundaries. The growth mode and properties of the In2O3 films prepared by plasma-enhanced ALD can be efficiently tuned by varying the substrate temperature.

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