For each material, a suitable boat, an appropriate temperature and a certain distance between the boat and the substrate should be used. For SiO2 you can use W boat and temperature of 1025 C at vacuum of 10 -6 mbar, or Al2O3 crucible

I just had this problem! 

I use a tungsten boat (supplier in link), 71 Amps, 6.5 Volts, filled with silicon powder in a background pressure of O2 (5E-4). At a distance of ~4 inches the rate of deposition is about 1 nm/min.

This has some SERIOUS problems though:

+Silicon alloys with tungsten so boats aren't really reusable

+Tungsten oxide sublimates so a shield needs to cover the bare tungsten (I use silicon wafer as a shield)

If you like I have a video of the silicon melting with these settings, it is kind of cool.

http://www.rdmathis.com/storev2/detail.asp?id=392

Parameters may be needed to be taken into account are;

Vacuum (10-6) torr, type of the substrate(if you want to anneal your film after preparation after 500 deg., glass substrate is not suitable) substrate holder (fixed or rotate), boat(tungsten, Mo or silica boat), shutter to cut the evaporation at the wanted thickness finally the deposition rate.

I wish this is useful and help you.

Yours

A. El-Denglawey

Thank you all.