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.
Highly Stable a-Si:H Films Deposited by Using Multi-Hollow Plasma Chemical Vapor Deposition
Hydrogenated amorphous silicon (a-Si:H) films of high stability against light exposure have been deposited by using a newly developed multi-hollow plasma chemical vapor deposition (CVD) method. Films deposited in the upstream region in the multi-hollow plasma CVD reactor are a-Si:H films without incorporating a-Si:H nano-particles (clusters), while those in the downstream region are a-Si:H films with incorporating clusters. A-Si:H films without clusters have a low initial defect density of 5 ×1015 cm-3 and keep the value even after 100 h exposure of intense light intensity of 240 mW/cm2, whereas a-Si:H films with clusters show a significant increase in defect density from its initial value of 5 ×1015 cm-3 to 2 ×1016 cm-3 after 100 h light exposure. These results indicate that suppression of clusters incorporated into films is the key to realizing highly stable a-Si:H films.
High speed turboprop aeroacoustic study (counterrotation). Volume 2: Computer programs
The isolated counterrotating high speed turboprop noise prediction program developed and funded by GE Aircraft Engines was compared with model data taken in the GE Aircraft Engines Cell 41 anechoic facility, the Boeing Transonic Wind Tunnel, and in the NASA-Lewis 8 x 6 and 9 x 15 wind tunnels. The predictions show good agreement with measured data under both low and high speed simulated flight conditions. The installation effect model developed for single rotation, high speed turboprops was extended to include counter rotation. The additional effect of mounting a pylon upstream of the forward rotor was included in the flow field modeling. A nontraditional mechanism concerning the acoustic radiation from a propeller at angle of attack was investigated. Predictions made using this approach show results that are in much closer agreement with measurement over a range of operating conditions than those obtained via traditional fluctuating force methods. The isolated rotors and installation effects models were combined into a single prediction program. The results were compared with data taken during the flight test of the B727/UDF (trademark) engine demonstrator aircraft.