Structural, Optical and Electrical Properties of μc-SiC:H Thin Films Deposited by the VHF-GD

1994 ◽  
Vol 358 ◽  
Author(s):  
Roger Fluckiger ◽  
J. Meier ◽  
A. Shah ◽  
J. Pohl ◽  
M. Tzolov ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Gas Phase ◽  
High Frequency ◽  
Input Power ◽  
Optical And Electrical Properties ◽  
Very High Frequency ◽  
Deposition Parameters ◽  
Temperature And Pressure ◽  
The Individual ◽  
Very High

ABSTRACTIn the present paper the authors present new results on thin (μc-SiC:H films deposited at low temperatures by the Very High Frequency - Glow Discharge technique (VHF-GD) at 70 MHz. The individual effects of each of the deposition parameters (methane and diborane gas phase ratios, input power, deposition temperature and pressure) are investigated with respect to the structural, optical and electrical properties of the films; the goal being the growth of optimised, thin μc-SiC:H layers for use as highly conductive and high gap window layers in solar cells.

Fabrication and Characterization of Cold Electron Emitter Based on Nanocrystalline Silicon Dots

2000 ◽  
Vol 638 ◽  
Author(s):  
K. Nishiguchi ◽  
X. Zhao ◽  
S. Oda
Keyword(s):  
Gas Phase ◽  
High Frequency ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Cold Electron ◽  
Very High Frequency ◽  
Electron Emitter ◽  
Fabrication And Characterization ◽  
Very High

AbstractA cold electron emitter has been made from nanocrystalline silicon (nc-Si) dots. Nc-Si dots are formed in the gas phase by very-high-frequency (VHF) plasma enhanced chemical vapor deposition (CVD). Electrons, accelerated by electric field, are ballistically transported through nc-Si and SiO2, then extracted into vacuum. Electron emission efficiency is optimized through varying nc-Si film thickness, surface roughness, and by short thermal oxidation.

Large Grain Size and High Deposition Rate for Microcrystalline Silicon Prepared by VHF-GD

1994 ◽  
Vol 358 ◽  
Author(s):  
P. Hapke ◽  
F. Finger ◽  
M. Luysberg ◽  
R. Carius ◽  
H. Wagner
Keyword(s):  
Grain Size ◽  
Deposition Rate ◽  
High Frequency ◽  
Excitation Frequency ◽  
Chemical Vapour ◽  
High Deposition Rate ◽  
Very High Frequency ◽  
Deposition Parameters ◽  
Plasma Excitation ◽  
Very High

ABSTRACTThe growth mechanism and material properties of -type µc-Si:H prepared with plasma enhanced chemical vapour deposition in the very high frequency range is investigated. By increasing the plasma excitation frequency the grain size, deposition rate and Hall mobility can be simultaneously increased without having to adjust other deposition parameters in particular the temperature. This effect is explained by an enhanced selective etching of amorphous tissue and grain boundary regions together with a sufficient supply of growth species at high frequency plasmas.

Silicon Carbon Alloys Produced by VHF and Conventional PECVD. A Comparison of their Properties.

1994 ◽  
Vol 336 ◽  
Author(s):  
G. Crovini ◽  
F. Demichelis ◽  
C.F. Pirri ◽  
E. Tresso ◽  
J. Meier ◽  
...  
Keyword(s):  
High Frequency ◽  
Urbach Energy ◽  
Energy Gap ◽  
Very High Frequency ◽  
Hydrogen Dilution ◽  
Deposition Parameters ◽  
Silicon Carbon ◽  
Defect Densities ◽  
Very High

ABSTRACTThe Very High Frequency (70 MHz) PECVD has recently proven its ability to produce Amorphous silicon with high deposition rates (10 Å/s) without affecting the quality of the Material. A comparative study of the optoelectronic properties of undoped silicon carbon alloys produced by Very High Frequency and by conventional RF (13.56 MHz) is carried out. Conductivity, infrared absorption, optical transmission and deep defect densities via PDS and ESR have been Measured. Deposition parameters under study aie methane fraction and hydrogen dilution. In contrast to conventional PECVD, we observe for VHF depositions an increase of the deposition rate with the addition of Methane. Larger energy gap and smaller Urbach energy values seem to indicate a better incorporation of carbon in the VHF case. A study of the degradation induced by light is also presented.

Enlarged Parameter Space by Use of VHF-GD for Deposition of Thin Type μc-Si:H Films

1996 ◽  
Vol 452 ◽  
Author(s):  
P. Torres ◽  
J. Meier ◽  
R. Flückiger ◽  
H. Keppner ◽  
A. Shah
Keyword(s):  
Gas Phase ◽  
High Frequency ◽  
Low Temperatures ◽  
High Electrical Conductivity ◽  
Very High Frequency ◽  
Transparent Films ◽  
Optically Transparent ◽  
Plasma Excitation ◽  
P Type ◽  
Very High

AbstractIn this paper new results on thin p - type μc-Si:H films deposited at low temperatures of 170 °C by the Very High Frequency - Glow Discharge technique (VHF-GD) are presented. The “tolerated” amount of diborane added in the gas phase ratio as well as the influence of three different plasma excitation frequencies (70, 100 and 130 MHz) in obtaining high electrical conductivity are investigated. The goal is to optimise very thin (< 400 Å) and hence optically transparent films by maintaining high conductivities for the application as window layers of solar cells.

scholarly journals WIDEBAND TRANSFORMER FOR MATCHING OF LOW-IMPEDANCE LOADS IN VERY HIGH FREQUENCY RANGE

Doklady BGUIR ◽  
2019 ◽  
pp. 43-49
Author(s):  
N. M. Naumovich ◽  
A. P. Joubko ◽  
M. V. Davydov ◽  
O. S. Maltsev
Keyword(s):  
Transmission Line ◽  
Standing Wave ◽  
High Frequency ◽  
Printed Circuit Board ◽  
Power Level ◽  
Input Power ◽  
Circuit Board ◽  
Very High Frequency ◽  
Input And Output ◽  
Very High

The article presents the results of preliminary research in the wideband transformer development for matching low-ohms loads in the very high frequency band with the use of a coupled transmission lines. The transmission line was produced with the using of a polyimide in the form of flexible printed circuit board. This way may be useful for wideband matching different cascades with custom values of input and output impedance in the wide band of frequencies and powers with use of a defining impedance capability with a load character in mind. On the first stage, the computer simulation of transformer with a transformer ratio 4:1 in the band (40–240 MHz) was completed for limiting values of input and output resistances – 50 and 12,5 Ohms respectively. Results of simulation give us the data about constructive parameters of the transmission line. The measurement technique for insertion loss was worked out. The reason of that is an impossibility of appliance standard methods with using a network vector analyzer. The prototyping was done and values of the standing wave ratio and inserting losses were obtained for different levels of the input power. According to received data, it can be affirmed, that the manufactured transformer provides the standing wave ratio better (lower) that two. Inserting losses vary from 0,02 to 1,54 dB depending from a input power level (1– 1000 mW). The obtained results afford ground for working continuation in this field – a development of wideband transformers for matching of low-ohms loads.

Control Architecture for 30MHz Linear Imaging Array

2003 ◽  
Author(s):  
R. L. Tutwiler ◽  
J. P. Stitt ◽  
K. K. Shung ◽  
Q. Wu ◽  
T. A. Ritter ◽  
...  
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Very High Frequency ◽  
Front End ◽  
High Speed Data Acquisition ◽  
Under Construction ◽  
The Individual ◽  
Test Phantom ◽  
Signal Interface ◽  
Very High

The purpose of this system is to have the capability to characterize the performance of very high frequency transducers and arrays. The analog front end is computer controlled by a set of de-multiplexers and multiplexers. The output of the multiplexer network is connected to a TGC array, which is interfaced to a high-speed data acquisition system. A software GUI (Graphical User Interface) has been designed to accomplish this task [1]. A programmable digital I/O interface allows collection of RF channel data and has the capability to be interfaced to a very high frequency analog beam-former under construction. The system front-end electronics (pulsers, receivers, T/R switches, multiplexers, and demultiplexers) have been characterized [2, 3]. The digital I/O signal interface has been integrated and tested. The hardware front end has been integrated to the array interface distribution panel. The individual transducer elements impulse responses have been evaluated and the performance of the array has been tested with a wire test phantom to characterize lateral and axial resolution.

Structural, Optical and Electrical Properties of μc-Si:H Very Thin Films Deposited by the VHF-GD Technique

1994 ◽  
Vol 336 ◽  
Author(s):  
Roger Flückiger ◽  
J. Meier ◽  
A. Shah ◽  
A. Catana ◽  
M. Brunel ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
High Frequency ◽  
Grazing Angle ◽  
Columnar Structure ◽  
Diffraction Reflection ◽  
X Ray Diffraction ◽  
Very High Frequency ◽  
X Ray ◽  
Very High

ABSTRACTIn this paper we present new results for very thin <p> μc-Si:H films (< 350 Å) deposited at low temperature (170 C) by the Very High Frequency - Glow Discharge technique (VHF-GD) at 70 MHz. First, the effect of boron doping on the growth and electrical properties of μc-Si:H very thin films is investigated, leading to an optimised value of about 0.6 % (B2H6/SiH4). Structural properties of an optimised thickness series ranging from 100 to 350 Å are studied using TEM, Raman, grazing angle X-ray diffraction/reflection and spectroscopie ellipsometry. Further, a columnar structure growth model for these very thin <p>-type μc-Si:H films will be proposed.

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