Effects of hydrogen dilution on electron density in multi-hollow discharges with magnetic field for A-Si:H film deposition
We have measured dependence of electron density n<inf>e</inf> on hydrogen dilution ratio R= [H<inf>2</inf>]/([SiH<inf>4</inf>]+[H<inf>2</inf>]) in the multi-hollow discharges with or without magnetic fields to obtain information about the deposition rate enhancement due to hydrogen dilution and applying the magnetic fields. The R dependence of the n<inf>e</inf> did not correlate with that of the deposition rate. The n<inf>e</inf> exponentially decreases with a distance from the discharges z. The n<inf>e</inf> decreases faster for higher R. These complicated behaviors of n<inf>e</inf> may be explained by electron attachment to the clusters generated in the SiH<inf>4</inf>+H<inf>2</inf> discharges. For R=0, the n<inf>e</inf> was almost same value regardless with or without magnetic fields. For R=1, n<inf>e</inf> with magnetic fields was 1/10 of that without magnetic fields. We also found that, for R=0, ne drastically decreased with increasing the z, while for R=1, ne showed a gradual decrease with z. The effects of applying magnetic fields on the deposition are unclear but applying the magnetic fields may affect the electron energy distribution.
Two-Dimensional Spatial Profile of Volume Fraction of Nanoparticles Incorporated Into a-Si:H Films Deposited by Plasma CVD
Using an optical-scanning method, we obtained 2-D spatial profile of deposition rate of hydrogenated amorphous silicon (a-Si:H) films deposited by a multihollow discharge plasma CVD with a high spatial resolution. From the profile, we deduced 2-D spatial profile of the volume fraction of nanoparticles incorporated into films, since nanoparticles affect optical and electronic properties of a-Si:H films.
Slotted Waveguide Antenna With Two Radiation Nulls
A design of a linear array antenna having two radiation nulls and otherwise omnidirectional radiation pattern is reported. A new configuration of a waveguide broad wall longitudinal slot doublet with positive and negative offsets with respect to the waveguide center line is used to design the array. This type of doublet produces two radiation nulls. Each of the null directions can be shifted at least up to plusmn25deg by proper choice of slot offset. Resonance and radiation characteristics of the proposed doublet are also presented. Finally, one linear array antenna consisting of seven doublets has been fabricated. Measurements show that the 15 dB null widths are 14.2deg and the null depths are at least 24.8 dB. Maximum gain ripple in the omnidirectional region is 1.75 dB.