Enhanced Surface Diffusion in Low-temperature a-Si:H Processing

ABSTRACTGlow discharge amorphous hydrogenated silicon (a-Si:H) prepared at near room temperature typically results in an inhomogeneous morphology that is undesirable for a number of thin film applications. The most commonly observed features of this include columnar morphology and surface roughness. This usually results from anodic deposition, where substrates are placed on the grounded electrode. We have discovered that placing substrates on the RF-powered electrode (referred to as cathodic deposition) offers a much wider processing range for homogenous growth than anodic growth. We have also found that the magnitude of the surface roughness and the bulk void fraction of both anodic and cathodic a-Si:H thin films processed at low-temperatures is proportional to ∼D/F, where D is the surface diffusivity and F, the adatom flux, though anodic and cathodic deposition affect these global parameters differently. Surface processes unique to cathodic deposition can enhance adatom surface diffusion, while diffusion during anodic deposition is fixed and cannot attain homogeneous growth at high adatom fluxes. Processing a-Si:H on the cathode, associated with enhanced adatom surface diffusion, allows for homogeneous growth even at high deposition rates that has benefits for a number of applications.

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Room-temperature electroluminescence from erbium-doped amorphous hydrogenated silicon

Journal of Luminescence ◽

10.1016/s0022-2313(98)00121-5 ◽

1998 ◽

Vol 80 (1-4) ◽

pp. 335-338 ◽

Cited By ~ 1

Author(s):

O.B Gusev ◽

M.S Bresler ◽

E.I Terukov ◽

K.D Tsendin ◽

I.N Yassievich

Keyword(s):

Room Temperature ◽

Hydrogenated Silicon ◽

Amorphous Hydrogenated Silicon ◽

Erbium Doped

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Room-temperature electroluminescence of erbium-doped amorphous hydrogenated silicon

Applied Physics Letters ◽

10.1063/1.118377 ◽

1997 ◽

Vol 70 (2) ◽

pp. 240-242 ◽

Cited By ~ 35

Author(s):

O. B. Gusev ◽

A. N. Kuznetsov ◽

E. I. Terukov ◽

M. S. Bresler, ◽

V. Kh. Kudoyarova ◽

...

Keyword(s):

Room Temperature ◽

Hydrogenated Silicon ◽

Amorphous Hydrogenated Silicon ◽

Erbium Doped

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

MRS Proceedings ◽

10.1557/proc-336-613 ◽

1994 ◽

Vol 336 ◽

Cited By ~ 3

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.

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Microstructure and Dangling Bond Defects in Amorphous Hydrogenated Silicon Deposited Near Room Temperature

MRS Proceedings ◽

10.1557/proc-258-191 ◽

1992 ◽

Vol 258 ◽

Cited By ~ 1

Author(s):

Man Ken Cheung ◽

Mark A. Petrich

Keyword(s):

Room Temperature ◽

Dangling Bond ◽

Optimum Conditions ◽

Band Tail ◽

Hydrogenated Silicon ◽

Photothermal Deflection Spectroscopy ◽

Amorphous Hydrogenated Silicon ◽

Photothermal Deflection ◽

Substrate Temperatures ◽

Absorption Measurements

ABSTRACTThe microstructure of high-density amorphous hydrogenated silicon (a-S.i:H) films deposited at 50°C substrate temperature was revealed by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies to be similar to that of “device-quality” a-Si:H films deposited at standard “optimum” conditions. However, optical absorption measurements of these low microstructure 50°C films with photothermal deflection spectroscopy indicate that they have higher densities of gap state defects and localized band tail states than “device-quality” films deposited at standard substrate temperatures. The correlation between the amount of microstructure and electronic properties is not unique. A low amount of microstructure is a necessary, but not sufficient, requirement for high electronic quality a-Si:H films.

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Room-temperature photoluminescence of erbium-doped amorphous hydrogenated silicon

10.1117/12.229154 ◽

1996 ◽

Author(s):

Mikhail S. Bresler ◽

Oleg B. Gusev ◽

V. K. Kudoyarova ◽

A. N. Kuznetsov ◽

Petr E. Pak ◽

...

Keyword(s):

Room Temperature ◽

Hydrogenated Silicon ◽

Room Temperature Photoluminescence ◽

Amorphous Hydrogenated Silicon ◽

Erbium Doped

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Room Temperature Light Induced Electron Spin Resonauce In Undoped Hydrogenated Amorphous Silicon (a-Si:H)

MRS Proceedings ◽

10.1557/proc-70-155 ◽

1986 ◽

Vol 70 ◽

Author(s):

R. Pandya ◽

S. Zafar ◽

E. A. Schiff

Keyword(s):

Electron Spin ◽

Room Temperature ◽

Small Shift ◽

Hydrogenated Silicon ◽

Transient Photocurrent ◽

Amorphous Hydrogenated Silicon ◽

Spin Resonance ◽

Absorption Studies ◽

G Value ◽

Hydrogenated Amorphous

ABSTRACTThe effects of illumination upon the absorption electron spin resonance spectrum of the dangling bond defect system have been studied in undoped amorphous hydrogenated silicon (a-Si:H). A small shift of the inhomogeneous envelope of the system towards higher g-value is observed at roomtemperature. The shift is not accompanied by a significant change in the signal. Results are reported which indicate that this shift is not due to illumination induced heating of the specimen or calibration changes of the spectrometer. The results may be related to previously reported optical bias effects upon transient photocurrent and photoinduced absorption studies.

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Room-Temperature Photoluminescence of Amorphous Hydrogenated Silicon Carbide Doped With Erbium

Physics and Applications of Non-Crystalline Semiconductors in Optoelectronics ◽

10.1007/978-94-011-5496-3_56 ◽

1997 ◽

pp. 474-474

Author(s):

E. I. Terukov ◽

V.kh. Kudoyarova ◽

A. N. Kuznetsov ◽

W. Fuhs

Keyword(s):

Silicon Carbide ◽

Room Temperature ◽

Hydrogenated Silicon ◽

Room Temperature Photoluminescence ◽

Amorphous Hydrogenated Silicon

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Room-temperature photoluminescence of amorphous hydrogenated silicon carbide doped with erbium

Journal of Non-Crystalline Solids ◽

10.1016/s0022-3093(98)00097-0 ◽

1998 ◽

Vol 227-230 ◽

pp. 488-492 ◽

Cited By ~ 7

Author(s):

E.I Terukov ◽

V.Kh Kudoyarova ◽

A.N Kuznetsov ◽

W Fuhs ◽

G Weiser ◽

...

Keyword(s):

Silicon Carbide ◽

Room Temperature ◽

Hydrogenated Silicon ◽

Room Temperature Photoluminescence ◽

Amorphous Hydrogenated Silicon

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Porous Silicon from Hydrogenated Amorphous Silicon: Comparison with Crystalline Porous Silicon

MRS Proceedings ◽

10.1557/proc-452-403 ◽

1996 ◽

Vol 452 ◽

Cited By ~ 9

Author(s):

J.-N. Chazalviel ◽

R. B. Wehrspohn ◽

I. Solomon ◽

F. Ozanam

Keyword(s):

Porous Silicon ◽

Room Temperature ◽

Quantum Confinement Effect ◽

Confinement Effect ◽

High Resistivity ◽

Hydrogenated Silicon ◽

Boron Doped ◽

Amorphous Hydrogenated Silicon ◽

Recombination Centers ◽

Hydrogenated Amorphous

AbstractDevice-grade, boron-doped amorphous hydrogenated silicon can be made microporous by anodization in ethanoic HF. The thickness of the porous layer is limited by an instability due to the high resistivity of the material. Amorphous porous silicon exhibits strong room-temperature photoluminescence around 1.5 eV even in samples containing a high density of non-radiative recombination centers. This demonstrates the presence of a spatial confinement effect, as opposed to quantum confinement effect for crystalline porous silicon. The temperature dependence of the luminescence intensity is also accounted for on the same grounds.

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Hydrogen Dilution effects on Amorphous Hydrogenated Silicon (a-Si:H) Prepared by Glow Discharge Near Room Temperature

MRS Proceedings ◽

10.1557/proc-219-721 ◽

1991 ◽

Vol 219 ◽

Author(s):

Man Ken Cheung ◽

Mark A. Petrich

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Glow Discharge ◽

Room Temperature ◽

Rf Power ◽

High Hydrogen ◽

Hydrogenated Silicon ◽

Hydrogen Dilution ◽

Amorphous Hydrogenated Silicon ◽

Dilution Effects

ABSTRACTWe report here the first phase of our attempt to deposit “device-quality” a-Si:H films by glow discharge near room temperature (50 °C). We have found that, at a low rf power density (40 mW/cm2) and high hydrogen/silane ratios (≥ 2), film quality is not uniquely determined by the substrate temperature, Ts. The microstructure of our low hydrogen content films as revealed by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies is similar to that of “device-quality” films deposited at standard Ts. The next phase of our work is to ascertain whether or not similar IR and NMR characteristics between our low Ts films and the standard Ts films imply also similar opto-electronic properties.

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