Fractal-Like Structures Present in Hydrogenated Amorphous and Microcrystalline Silicon

1989 ◽  
Vol 164 ◽  
Author(s):  
M.J. Geerts ◽  
R.C. van Oort ◽  
J.C. van den Heuvel
Keyword(s):  
Plasma Etching ◽  
Hydrogen Plasma ◽  
Structural Disorder ◽  
Rf Plasma ◽  
Microcrystalline Silicon ◽  
Nmr Studies ◽  
Typical Size ◽  
Small Crystals ◽  
Hydrogenated Amorphous ◽  
Closed Network

AbstractIn hydrogenated amorphous silicon NMR studies indicate a twophase structural inhomogenity. Hydrogenated microcrystalline films consist of small crystals with a typical size of 100 Å, embedded in an amorphous web. A hydrogen rf plasma is able to etch both type of films, but with different etch rates. The more crystalline parts of a film are etched more slowly, which makes hydrogen plasma etching a technique that can reveal structural inhomogenities and differences in structural disorder as present, both in amorphous and in microcrystalline silicon films.Amorphous and microcrystalline films were etched and fractal-like structures were visible when using a SEM at a magnification of 20000 times. In microcrystalline films the fractals form a closed network. The number and typical size of the fractals present in amorphous films can be influenced by the conditions during the deposition.

Light-Induced Effects on Fluorinated Amorphous and Microcrystalline Silicon Films

1996 ◽  
Vol 420 ◽  
Author(s):  
Hong-Seok Choi ◽  
Keun-Ho Jang ◽  
Jhun-Suk Yoo ◽  
Min-Koo Han
Keyword(s):  
Band Gap ◽  
Vapor Deposition ◽  
Optical Band Gap ◽  
Silicon Film ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Microcrystalline Silicon ◽  
Amorphous Silicon Film ◽  
Hydrogenated Amorphous

AbstractThe fluorinated amorphous and microcrystalline silicon (a,μc-Si:H;F) films have been prepared by rf plasma enhanced chemical vapor deposition (PECVD) with SiH 4 and SiF 4 gas mixtures. The stretching Si-O (1085 cm-1) and SiH2 (2100 cm-1) bands estimated from infrared (IR) spectroscope data have related to the evolution of crystallinity and the optical band gap was shifted by introducing Si-O bonds. The sub-band gap absorption coefficient in a,μc-Si:H;F films was about one order lower than that in hydrogenated amorphous silicon film (a-Si:H). The subband gap absorption in a-Si:H;F film was comparable to that in tic-Si:H;F films. The lightinduced degradation of a,μc-Si:H;F films were also suppressed.

Etching Properties of Hydrogenated Amorphous Silicon

1991 ◽  
Vol 219 ◽  
Author(s):  
Y. S. Tsuo ◽  
Y. Xu ◽  
D. W. Baker ◽  
S.K Deb
Keyword(s):  
Amorphous Silicon ◽  
Plasma Etching ◽  
Hydrogen Content ◽  
Chemical Etching ◽  
Isopropyl Alcohol ◽  
Hydrogen Plasma ◽  
Hydrogenated Amorphous Silicon ◽  
Wet Chemical ◽  
Wet Chemical Etching ◽  
Hydrogenated Amorphous

ABSTRACTWe have studied wet-chemical and dry etching properties of doped and undoped hydrogenated amorphous silicon (a-Si:H) films with bonded hydrogen content varying from 0 to 20 at.%. Etching processes studied include (1) wet-chemical etching using solutions of KOH, isopropyl alcohol (IPA), and H2O, (2) hydrogen plasma etching, and (3) XeF2 vapor etching.

Increase of Hydrogen-Radical Density and Improvement of The Crystalline Volume Fraction of Microcrystalline Silicon Films Prepared by Hot-Wire Assisted Pecvd Method

2000 ◽  
Vol 609 ◽  
Author(s):  
Norimitsu Yoshida ◽  
Takashi Itoh ◽  
Hiroki Inouchi ◽  
Hidekuni Harada ◽  
Katsuhiko Inagaki ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Hot Wire ◽  
Dilution Ratio ◽  
Microcrystalline Silicon ◽  
Hydrogen Dilution ◽  
Hydrogen Radical ◽  
Hydrogen Radicals ◽  
Hydrogenated Amorphous

ABSTRACTHigher crystalline Si volume fractions in hydrogenated microcrystalline silicon ( µc-Si:H) films have been achieved by the hot-wire assisted plasma enhanced chemical vapor deposition (HWA-PECVD) method compared with those in films by conventional PECVD. µc-Si:H films can also be prepared by HWA-PECVD under typical conditions used for preparing hydrogenated amorphous silicon (a-Si:H) films by PECVD, in which the hydrogen-dilution ratio (H2 / SiH4) is ∼ 10. The hot wire seems to produce hydrogen radicals. As a result, the HWA- PECVD method can control hydrogen-radical densities in the RF plasma, and this method can also control the ratio of hydrogen coverage at the surface of the film.

Hydrogen plasma etching of amorphous and microcrystalline silicon

1987 ◽  
Vol 23 (18) ◽  
pp. 967 ◽  
Author(s):  
R.C. van Oort ◽  
M.J. Geerts ◽  
J.C. van den Heuvel ◽  
J.W. Metselaar
Keyword(s):  
Plasma Etching ◽  
Hydrogen Plasma ◽  
Microcrystalline Silicon

Material Structure of Microcrystalline Silicon Deposited with an Expanding Thermal Plasma

2003 ◽  
Vol 762 ◽  
Author(s):  
C. Smit ◽  
D.L. Williamson ◽  
M.C.M. van de Sanden ◽  
R.A.C.M.M. van Swaaij
Keyword(s):  
Thermal Plasma ◽  
Hydrogen Plasma ◽  
Plasma Chemistry ◽  
Plasma Source ◽  
Growth Direction ◽  
Interaction Time ◽  
Material Structure ◽  
Average Particle ◽  
Microcrystalline Silicon ◽  
X Ray

AbstractExpanding thermal plasma CVD (ETP CVD) has been used to deposit thin microcrystalline silicon films. In this study we varied the position at which the silane is injected in the expanding hydrogen plasma: relatively far from the substrate and close to the plasma source, giving a long interaction time of the plasma with the silane, and close to the substrate, resulting in a short interaction time. The material structure is studied extensively. The crystalline fractions as obtained from Raman spectroscopy as well as from X-ray diffraction (XRD) vary from 0 to 67%. The average particle sizes vary from 6 to 17 nm as estimated from the (111) XRD peak using the Scherrer formula. Small angle X-ray scattering (SAXS) and flotation density measurements indicate void volume fractions of about 4 to 6%. When the samples are tilted the SAXS signal is lower than for the untilted case, indicating elongated objects parallel to the growth direction in the films. We show that the material properties are influenced by the position of silane injection in the reactor, indicating a change in the plasma chemistry.

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

STM on doped and undoped hydrogenated amorphous and microcrystalline silicon films

1992 ◽  
Vol 42-44 ◽  
pp. 1398-1402 ◽  
Author(s):  
W. Zimmermann-Edling ◽  
R. Wiesendanger ◽  
F. Finger ◽  
K. Prasad ◽  
A. Shah
Keyword(s):  
Silicon Films ◽  
Microcrystalline Silicon ◽  
Hydrogenated Amorphous

A Chemical Perspective of GaN Polarity: The use of Hydrogen Plasma Dry Etching Versus NaOH Wet Etching to Determine Polarity

2002 ◽  
Vol 722 ◽  
Author(s):  
Maria Losurdo ◽  
MariaMichela Giangregorio ◽  
Pio Capezzuto ◽  
Giovanni Bruno ◽  
Gon Namkoong ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Plasma Etching ◽  
Hydrogen Plasma ◽  
Dry Etching ◽  
Surface Reactivity ◽  
Wet Etching ◽  
Hydrogen Treatment

AbstractThe use of dry hydrogen plasma etching is evaluated for determination of GaN polarity and critically compared to wet etching in NaOH. It is shown that hydrogen plasma etching is effective in revealing inversion domains (IDs) and some types of dislocations. This is because the surface morphology is unchanged by the hydrogen treatment, and, hence, the surface reactivity is not masked.

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