Chemical analysis of a silicon crystal reveals gallium at a level of 3.091×10−4 atomic percent. Assuming that the concentration of thermally excited charge carriers from the Si matrix is negligible, what is the density of free charge carriers (free carriers/cm3) in this Si crystal?

Confused here too
arel
14 December 2012
Go back to H2P2
arel
15 December 2012
Type back if understood
arel
15 December 2012
I still don't have the answer
lisa2266
15 December 2012
did you get problem 3, if so i can help with 9
arel
15 December 2012
and others
arel
15 December 2012
lisa2266
15 December 2012
never mind i alredy got it
arel
15 December 2012
lisa2266
15 December 2012
1.54E17
arel
15 December 2012
Thanks so much how did u get the answer
lisa2266
15 December 2012
If you find can you please explain 3?
arel
15 December 2012
I have all the answers except #1 and #3
lisa2266
15 December 2012
I have 1
arel
15 December 2012
Some of the problems are different here is mine. You wish to increase the carbon content of a slab of steel by exposing it to a carburizing atmosphere at elevated temperature. The carbon concentration in the steel before carburization is 359.5 ppm and is initially uniform through the thickness of the steel. The atmosphere of the carburizing furnace maintains a carbon concentration of 6695.0 ppm at the surface of the steel. Calculate the time required to carburize steel so that the concentration of carbon at a depth of 38.0 x 10-2 cm is one half the value of the carbon concentration at the surface. The diffusion coefficient of carbon in steel is 3.091 x 10-7 cm2/s at the carburizing temperature. Express your answer in hours.
lisa2266
15 December 2012
I have diff but i can explain the steps
arel
15 December 2012
If you want
arel
15 December 2012
I would appreciate that
lisa2266
15 December 2012
Butu can you help me
lisa2266
15 December 2012
if you guys work out problem 3, or the steps on how to work it out, that would be amazing, it's the onle one i can't do atm
pngo2222
15 December 2012
How would you work out this question with gallium at a level of 3.091x10^-2?
ozymandias
16 December 2012
Never mind; I've just figured it out.
ozymandias
16 December 2012
how would it work for 3.091*10^-3?
mb
17 December 2012