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.

Optical absorption in PECVD deposited thin hydrogenated silicon in light of ordering effects

Open Physics ◽  
2009 ◽  
Vol 7 (2) ◽  
Author(s):  
Jarmila Müllerová ◽  
Veronika Vavruňková ◽  
Pavel Å utta
Keyword(s):  
Chemical Vapour ◽  
Optical Transmittance ◽  
Band Gap Energy ◽  
Absorption Coefficients ◽  
Hydrogenated Silicon ◽  
Transmittance Spectra ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Ordering Effects ◽  
Amorphous Hydrogenated Silicon

AbstractWe report results obtained from measurements of optical transmittance spectra carried out on a series of silicon thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) from silane diluted with hydrogen. Hydrogen dilution of silane results in an inhomogeneous growth during which the material evolves from amorphous hydrogenated silicon (a-Si:H) to microcrystalline hydrogenated silicon (µc-Si:H). Spectral refractive indices and absorption coefficients were determined from transmittance spectra. The spectral absorption coefficients were used to determine the Tauc optical band gap energy, the B factor of the Tauc plots, E 04 (energy at which the absorption coefficient is equal to 104 cm−1), and the Urbach energy as a function of the hydrogen dilution. The results were correlated with microstructure, namely volume fractions of the amorphous and crystalline phase with voids, and with the grain size.

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.

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.

Influence of Substrate Temperature on the Properties of A-Si:H P-Layers Obtained from Trimethylboron

1994 ◽  
Vol 336 ◽  
Author(s):  
J. Puigdollers ◽  
J.M. Asensi ◽  
J. Bertomeu ◽  
J. Andreu ◽  
J.C. Delgado
Keyword(s):  
Substrate Temperature ◽  
Optical Transmission ◽  
Boron Content ◽  
Secondary Ion Mass Spectrometry ◽  
Dark Conductivity ◽  
Film Properties ◽  
Atom Concentration ◽  
Influence Of Substrate ◽  
Secondary Ion ◽  
Marked Dependence

ABSTRACTa-Si:H p-layers doped by trimethylboron (TMB) were obtained by PECVD in a monochamber reactor with a rotating substrate holder. The influence of the substrate temperature (Ts) on the film properties was systematically studied for two different doping gas concentrations. The incorporation of boron, hydrogen and carbon was studied by Secondary Ion Mass Spectrometry (SIMS). Optical properties were determined by means of Photothermal Deplection Spectroscopy (PDS) and optical transmission. Dark conductivity (aj and activation energy (Eact) were measured electrically. Our results show that Σd has a marked dependence on substrate temperature, although boron atom concentration depends only slightly on Ts. The optical gap for samples obtained at the higher concentration also depends on Ts and its dependence is related to the hydrogen content, as boron content does not change. P-i-n diodes were obtained with the p-layer deposited from TMB.

The doping of a-Si:H with liquid boron and phosphorus sources

1992 ◽  
Vol 258 ◽  
Author(s):  
M. Albert ◽  
K. Schade ◽  
W. Beyer
Keyword(s):  
Dark Conductivity ◽  
Electron Donors ◽  
Gas Mixture ◽  
Mixture Ratio ◽  
Hydrogenated Silicon ◽  
Capacitively Coupled ◽  
Optical Gap ◽  
Amorphous Hydrogenated Silicon ◽  
Phosphorus Sources ◽  
Gas Cylinders

ABSTRACTThe conductivity control of amorphous hydrogenated silicon (a-Si:H) by incorporation of electron donors or acceptors is prerequisite for the application of these layers in devices. The doping sources B2H6 and PH3 which are usually highly toxic are substituted by not dangerous boron and phosphorus liquid sources based on hydro-carbons. The avoidance of gas cylinders and expensive safety measure techniques is another advantage of these liquids.In this paper we have studied the influence of boron, phosphorus and carbon on the electrical, photoelectrical and optical properties. The layers were produced in a capacitively coupled reactor in a silan-doping gas mixture. The maximum of the dark conductivities (300K) of the p- and n-type a-SiC.,:H layers was 10-5 and 103 (Ωcm)-1, respectively, the activation energys decreases to 0.4 and 0.2 eV respectively. With a high quantity within the range of doping gas in the mixture, the carbon determines the layer properties. At a gas mixture ratio of 1:1 ( silan: doping gas) the optical gap expands to 2.7 eV and the dark conductivity decreases below 10∼13 (Ωcm)-1.

CW CO2 laser CVD of amorphous hydrogenated silicon (a-Si:H): influence of the deposition geometry

1992 ◽  
Vol 54 ◽  
pp. 30-34 ◽  
Author(s):  
E. Golusda ◽  
R. Lange ◽  
K.-D. Lühmann ◽  
G. Mollekopf ◽  
M. Wacker ◽  
...  
Keyword(s):  
Co2 Laser ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Cw Co2 Laser ◽  
Laser Cvd
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