Useful Links:

Some good semiconductor materials websites:

http://www.ioffe.ru/SVA/NSM/Semicond/index.html

http://www.ee.byu.edu/cleanroom/EW_ternary.phtml

Some useful online calculators:

Does almost anything:  www.wolframalpha.com

Freq/Wavelength/Energy:

http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/cnvcalc.htm

http://www.cactus2000.de/uk/unit/masswav.shtml