Question #1 : A customer left a piece of mysterious semiconductor material and w
ID: 1284900 • Letter: Q
Question
Question #1 : A customer left a piece of mysterious semiconductor material and wanted to know whether this is n-type or p-type material. The only info given by the customer is that this material is made with silicon and three other elements. Your colleague did a simple experiment and found that: the electron concentration in this material at T = 300 Kelvin is n0 = 2 x10^5 cm^-3. Can you answer the customer's question based on the above info?
Question #2: A p-type silicon is doped with boron at a concentration of Na = 1x10^16 cm^-3. Determine the fraction of total holes still in the acceptor states in silicon at T = 250 Kelvin if the degeneracy factor is g = 4.
Explanation / Answer
The intrinsic carrier concentration of silicon at 300k ni=1010
But here given n0= 2x105 i.e. n0<ni; to satisfy mass action law p0>ni
therefore it is a p-type semiconductor
2) p0=ni2/n0
p0=5x1015cm-3
Therefore unionized acceptor =5x1015cm-3
Therefore fraction of hole acceptor states=5x1015 /1016 /4=0.125