Find Fermi Level Pos. of Si w/ 6x1015 Donors & 2x1015 Acceptors @ 300K

[magnifik]

Si is doped with 6 x 10¹⁵ cm^-3 donors and 2 x 10¹⁵ cm^-3 acceptors. Find the position of the Fermi level with respect to E_i at 300 K.

i know the equations are
(for n-type) E_F = kT ln(N_D/n_i) + E_i
(for p-type) E_F = kT ln(n_i/N_A) + E_i

however, since the problem gives me both donors and acceptors, how do i know which one to use? i am thinking since there are more donors than acceptors, i use the equation for n-type...not sure if this is correct though.

 

[Maxim Zh]

All the acceptor states will be occupied by electrons come from donors. So the semiconductor will behave like n-type one with
<br /> n&#039;_{\text{donor}} = n_{\text{donor}} - n_{\text{acceptor}}<br />