[材料] 有一題作業不會~"~請各位大大幫忙

[chihow0520 (異鄉人)]

最近上到diffusion..
這個章節不是很瞭解
老師出了一個題目不知道該怎麼解
請各位大大 賜教
You are diffusing phosphorus,P(an n-type dopan) into
undoped silicon wafer in a 1100 degree C furnace using
a continuous supply of phosphine gas PH3 that establishes
a surface P concentration of 5.00*10^18 atoms*cm^-3
1)is this a case of steady-state or non-steady state diffusion? why?

2)after the wafer has been in the furnace for 80mins,
phosphorus has had a chance to diffuse into the wafer. qualitatively plot
the concentration of phosphorus as a function of  depth from the surface.
what is the name of the mathematical function that has the same shape as
this concentration profile?

3)at same time as in the graph you drew for part2( after 80mins), there
will be a point withn the wafer where the P concentration is exactly
0.60 of surface P concentration. Calculate this depth, in nm.
The pre-exponential coefficient Dο, for diffusion of P in Si
is 10.5cm^2S^-1 and the activation energy of this diffusion is 3.69eV
(per atom)

希望各位大大能幫忙小弟
解這一題....

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