Solar-Cell Suitable μc-Si Films Grown by ECR-CVD

2000 ◽  
Vol 609 ◽  
Author(s):  
M. Birkholz ◽  
E. Conrad ◽  
K. Lips ◽  
B. Selle ◽  
I. Sieber ◽  
...  
Keyword(s):  
Electron Cyclotron Resonance ◽  
Film Growth ◽  
Dark Conductivity ◽  
Film Deposition ◽  
Degree Of Crystallinity ◽  
High Hydrogen ◽  
Hydrogen Dilution ◽  
Impurity Contamination ◽  
Si Films ◽  
High Degree

ABSTRACTThe preparation of μc-Si films from SiH4-H2 mixtures by electron-cyclotron resonance (ECR) CVD at deposition temperatures ≤ 400°C on foreign substrates is reported. Deposition conditions were identified for which Si films with a high degree of crystallinity were grown as was confirmed by Raman spectroscopy. A factorial analysis was carried out, for which the influence of deposition temperature, microwave power, hydrogen dilution and total pressure on film growth were investigated. Samples of optimized crystallinity were prepared in a lowpressure and high-hydrogen dilution regime. In-plane grain sizes were measured by TEM and found to be on the order of 10 - 12 nm. Next to the optimization of crystallinity several sources of impurity contamination during film deposition were identified and eliminated. Intrinsic μc-Si layers could be prepared under these conditions that exhibited a dark conductivity σd of 2 × 10-7 S/cm and photosensitivity σph/σd of 150. It is concluded that ECR CVD is capable of producing intrinsic layers with electronic properties as necessary for use in state-of-the-art n-i-p μc-Si solar cells.

Afm/Tem Investigation of Low Temperature Polycrystalline Silicon Grown by ECR-CVD

1995 ◽  
Vol 406 ◽  
Author(s):  
H. L. Hsiao ◽  
K. C. Wang ◽  
L. W. Cheng ◽  
A. B. Yang ◽  
T. R. Yew ◽  
...  
Keyword(s):  
Low Temperature ◽  
Polycrystalline Silicon ◽  
Electron Cyclotron Resonance ◽  
Film Growth ◽  
Chemical Vapor ◽  
Plan View ◽  
3 Dimensional ◽  
High Resolution Tem ◽  
Si Films ◽  
Polycrystalline Silicon Films

AbstractThe polycrystalline silicon films were deposited by electron cyclotron resonance chemical vapor deposition (ECR-CVD) with hydrogen dilution at 250°C and without any thermal annealing. The surface morphology and the microstructure of the poly-Si films are investigated by atomic force microscopy (AFM), plan-view transmission electron microscopy (TEM), crosssectional TEM and high resolution TEM (HRTEM). The low temperature poly-Si films deposited by ECR-CVD show a special leaf-like grain shape (plan-view) and an upside-down cone shape (3-dimensional view). The grains in the poly-Si films have preferred orientation of <112> and the longer side of the leaf-like grain is direction and the shorter side is direction. Lattice bending and interruption are found in the films. The arrangement of the atoms on the grains are well ordered, while atoms in the interfacial regions are randomly distributed. A simple grain formation model based on growth rate differences between different planes and etching effect can explain the film growth mechanism and the formation of the special grain geometry.

¼c Silicon Thin Films Deposited by Remote Plasma Enhanced Chemical Vapor Deposition Process

1990 ◽  
Vol 192 ◽  
Author(s):  
C. Wang ◽  
G. N. Parsons ◽  
S. S. Kim ◽  
E. C. Buehler ◽  
R. J. Nemanich ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Substrate Material ◽  
Degree Of Crystallinity ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Type C ◽  
Si Films ◽  
P Type

ABSTRACTIn an earlier study, we deposited ¼c-Si thin films by reactive magnetron sputtering (RMS). Here we extend our studies to the deposition of both undoped and high conductivity N-type and P-type ¼c-Si thin films by a remote PECVD. We show that ¼c-Si films can be deposited by bringing hydrogen, H2, into the source gas mixtures. The H2 could introduced by either upstream in a He/H2 mixture and directly plasma excited, or downstream, and be remotely excited along with the silane, SiH4, feed gas. The degree of crystallinity is shown to depend on the hydrogen dilution, the substrate temperature and the substrate material.

In Situ Diagnostics of Methane/Hydrogen Plasma Interactions with Si(100)

1999 ◽  
Vol 569 ◽  
Author(s):  
H. L. Duan ◽  
Stacey F. Bent
Keyword(s):  
Silicon Surface ◽  
Electron Cyclotron Resonance ◽  
Hydrogen Plasma ◽  
Film Deposition ◽  
Diagnostic Study ◽  
Methane Pressure ◽  
Plasma Interactions ◽  
Ecr Plasma ◽  
Hydrogen Dilution

ABSTRACTMethane/hydrogen plasmas have been reported to be sources both for a-C:H film deposition and for compound semiconductor etching. In this work, an in situ diagnostic study of methane/hydrogen plasma interactions with a silicon surface is carried out, focusing on the effect of hydrogen dilution. A remote electron cyclotron resonance (ECR) plasma using a H2/Ar mixture excites methane gas near a Si(l 00) substrate. In situ multiple internal reflection Fourier transform infrared (MIR-FTIR) spectroscopy is used to probe the surface species at different hydrogen dilution ratios. We find that at low methane pressure without hydrogen dilution, a-C:H films are deposited. With H2 dilution, the results suggests that some sputter/etching of the silicon surface occurs. Hence, methyl groups are identified as potential etchants for silicon materials. The data suggest that there is a competition between etching and deposition chemistry which depends strongly upon the methane pressure and hydrogen ratio in the plasma.

Microstructural Defects of Device Quality Hot-Wire Cvd Poly-Silicon Films

1999 ◽  
Vol 557 ◽  
Author(s):  
J.K. Rath ◽  
F.D. Tichelaar ◽  
R.E.I. Schropp
Keyword(s):  
Volume Fraction ◽  
Nucleation Density ◽  
Hot Wire ◽  
Compact Structure ◽  
High Oxygen Content ◽  
High Hydrogen ◽  
Hydrogen Dilution ◽  
Si Films ◽  
Spherical Voids ◽  
Steel Substrates

AbstractTwo types of poly-Si:H thin films made by Hot Wire CVD have been evaluated with respect to utilisation in solar cells. Poly-Si:H films made at high hydrogen dilution are highly porous and have large interconnected voids. The void density is 25000/μm-3 as determined by XTEM. On the other hand, poly-Si:H layers made at low hydrogen dilution have a compact structure and a much smaller density of voids. In these films, two types of voids exist: globular voids smaller than 15 nm, and elongated voids, often located between columns of large crystals of 150-250 nm wide at the top. The density for the 5 - 15 nm spherical voids is usually -50/μm3, but larger concentrations often occur locally, up to 1000/pm3, i.e., 0.05% volume fraction. High oxygen content in the poly-Si films made at high hydrogen dilution is largely due to post deposition intrusion of water vapour through the interconnected voids. Profiled layers are made by depositing device quality poly-Si:H layers (low hydrogen dilution) on top of a seed layer (high hydrogen dilution) of high nucleation density. Cells incorporating profiled poly-Si:H films as i-layers at a deposition rate of 0.5 nm/s were made on stainless steel substrates in the configuration SS/n-μc-Si:H(PECVD)/i-poly-Si:H(HWCVD)/p-μc-Si:H(PECVD)/ITO. For our n-i-p solar cell with poly-Si i-layer we obtained an efficiency of 4.41% and a FF of 0.607. Due to native surface texture a current density of 19.95 mA/cm2 is generated in only ~1.22 μm thick i-layer without back reflector.

In-Situ Mass Spectroscopy of ECR Silane Plasmas for Amorphous and Microcrystalline Silicon Growth

2000 ◽  
Vol 609 ◽  
Author(s):  
Young J. Song ◽  
Elena Guliants ◽  
Hak-Gyu Lee ◽  
Wayne A. Anderson
Keyword(s):  
Mass Spectroscopy ◽  
Atomic Hydrogen ◽  
Dark Conductivity ◽  
Input Power ◽  
Chamber Pressure ◽  
Film Properties ◽  
Hydrogen Dilution ◽  
Silicon Growth ◽  
Si Films

ABSTRACTECR silane plasmas for the deposition of a-Si:H and μc-Si films were investigated by in-situ mass spectroscopy (MS) using a quadrupole residual gas analyzer. The results showed that the intensities of ionic and neutral species (H, H2, He, Ar, Si and SiHx) in the 2 % SiH4/He plasma are strongly dependent on the deposition conditions such as chamber pressure, input power and hydrogen dilution. In all cases, the prevalence of Si ions was observed over SiH, SiH2 and SiH3 ions, suggesting a high decomposition rate of the silane in the plasma. In particular, the population of atomic hydrogen in the plasma seems to play a key role in the properties of both a-Si:H and μc-Si films. For example, the increased intensity of atomic hydrogen, compared to that of molecular hydrogen, resulted in the better quality a-Si:H film, showing a higher photo and dark conductivity ratio of ~105. The intensity of the hydrogen species was especially sensitive to the chamber pressure. The correlation between MS spectra and film properties is presented.

Ultrafast Deposition of Crystalline Si Films Using a High Density Microwave Plasma

2010 ◽  
Vol 1245 ◽  
Author(s):  
Haijun Jia ◽  
Michio Kondo
Keyword(s):  
Film Growth ◽  
Microwave Plasma ◽  
Crystalline Silicon ◽  
Plasma Source ◽  
Ambient Air ◽  
Film Deposition ◽  
High Density ◽  
Silicon Films ◽  
Reduced Pressure ◽  
Si Films

AbstractA multi-pressure microwave plasma source is developed and is applied for the fast deposition of crystalline silicon films. In this paper, the plasma source is diagnosed firstly. Electron density, electron temperature and discharge gas temperature of the plasmas generated in ambient air are studied using optical emission spectroscopy (OES) method. By using the high density microwave plasma source, depositions of crystalline silicon films from SiH4+He mixture at reduced pressure conditions are investigated systematically. After optimizing the film deposition conditions, highly crystallized Si films are deposited at a rate higher than 700 nm/s. We also find that the deposited films are fully crystallized and crystalline structure of the deposited film evolves along the film growth direction, i.e. large grains in surface region while small grains in the bottom region of the film. Based on the observed results, a possible mechanism, the annealing-assisted plasma-enhanced chemical vapor deposition, is proposed to describe the film growth process.

Deposition of Hydrogenated Si Films by Hydrogenation of the SiO2 Surface and Hydrogen Dilution with PE-CVD and ECR-CVD

1994 ◽  
Vol 345 ◽  
Author(s):  
Kun-Chih Wang ◽  
Tri-Rung Yew ◽  
Huey-Liang Hwang
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Chemical Vapor ◽  
Hydrogen Dilution ◽  
Surface Steps ◽  
Transmission Electron ◽  
Temperature Deposition ◽  
Si Films

AbstractThis paper presents the results of low temperature deposition of poly-Si films deposited on SiO2 layers. Hydrogen dilution, hydrogen atom treatment, and hydrogenation of the SiO2 surface steps were applied to deposit the Si films. The above treatment steps were usually used in the plasma enhanced chemical vapor deposition and they were extended to be used in the electron cyclotron resonance chemical vapor deposition to identify the grain growth effects. The nucleation and microstructure of the silicon films were observed by cross-section transmission electron microscopy (XTEM).

Growth and Electronic Properties in Hot Wire Deposited Nanocrystalline Si Solar Cells

2007 ◽  
Vol 989 ◽  
Author(s):  
Kamal Muthukrishnan ◽  
Vikram Dalal ◽  
Max Noack
Keyword(s):  
Electronic Properties ◽  
Defect Density ◽  
Grain Structure ◽  
Degree Of Crystallinity ◽  
Hot Wire ◽  
High Hydrogen ◽  
Filament Temperature ◽  
Random Nucleation ◽  
Hydrogen Dilution ◽  
High Filament

AbstractWe report on the growth and properties of nanocrystalline Si:H grown using a remote hot wire deposition system. Unlike previous results, the temperature of the substrate is not significantly affected by the hot filament in our system. The crystallinity of the growing film and the type of grain structure was systematically varied by changing the filament temperature and the degree of hydrogen dilution. It was found that high hydrogen dilution gave rise to random nucleation and <111> grain growth, whereas lower hydrogen dilution led to preferable growth of <220> grains. Similarly, a high filament temperature gave rise to preferential <111> growth compared to lower filament temperature. The electronic properties such as defect density and minority carrier diffusion length were studied as a function of the degree of crystallinity. It was found that the lowest defect density was obtained for a material which had an intermediate range of crystallnity, as determined from the Raman spectrum. Both highly amorphous and highly crystalline materials gave higher defect densities. The diffusion lengths were measured using a quantum efficiency technique, and were found to be the highest for the mid-range crystalline material. The results suggest that having an amorphous tissue surrounding the crystalline grain helps in passivating the grain boundaries.

The Study on Microstructure by NMR, FTIR, Raman, Conductivity and Optical Bandgap in Hydrogenated Amorphous Silicon Prepared by Novel Fabrication Methods

1992 ◽  
Vol 258 ◽  
Author(s):  
K. C. Hsu ◽  
H. Chang ◽  
C. S. Hong ◽  
H. L. Hwang
Keyword(s):  
Hydrogen Atom ◽  
Substrate Temperature ◽  
Silicon Film ◽  
Dark Conductivity ◽  
Optical Bandgap ◽  
Degree Of Crystallinity ◽  
Hydrogen Treatment ◽  
Compact Structure ◽  
Hydrogen Incorporation ◽  
Hydrogen Dilution

ABSTRACTIt was found that hydrogen dilution in the SiH4/H2 mixture tend to show a sharp line-shape in the NMR spectra as the substrate temperature is higher than 300 °C. The hydrogen-atom-treatment method also produces the same effect at a lower substrate temperature about 250°C. The Raman scattering spectra show that the hydrogen-atom-treatment creates the microcrystalline structure at a temperature higher than 250°C while hydrogen dilution produces mixed phases containing amorphous phase and a small quantity of micro-crystalline phase. Together with the optical bandgap narrowing, the increase of the dark conductivity and the reduction of photo-to-dark conductivity ratio, these samples indicate that with more hydrogen incorporation during deposition and plasma hydrogen treatment, these films possess a much compact structure, and the degree of crystallinity of hydrogenated silicon film was found to be systematically changed.

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