Update 14_doping_and_devices.md - typo

src/14_doping_and_devices.md

@@ -74,7 +74,7 @@ draw_classic_axes(ax, xlabeloffset=.2)
 ```
 
 All donor/acceptor states at the same energy:
-$$g_A(E) = N_A \delta(E-E_A),\quad g_D(E) = N_D \delta(E- (E_G - E_D))$$
+$$g_A(E) = N_A \delta(E-E_A),\quad g_D(E) = N_D \delta(E- E_D)$$
 
 How large can $N_D/N_A$ be? The distance between donors should be such that the states don't overlap, so the distance must be much larger than 4 nm. Therefore **maximal** concentration of donors before donor band merges with conduction band is $N_D \lesssim (1Å/4\textrm{nm})^3 \sim 10^{-5}\ll N_C$.
 
@@ -86,7 +86,7 @@ $$n_e - n_h + n_D - n_A = N_D - N_A$$
 
 We already know $n_e$ and $n_h$.
 
-$$n_D = N_D \frac{1}{e^{-(E_D-E_F)/kT} + 1}, n_A = N_A \frac{1}{e^{-(E_A+E_F)/kT} + 1}$$
+$$n_D = N_D \frac{1}{e^{(E_D-E_F)/kT} + 1}, n_A = N_A \frac{1}{e^{-(E_A+E_F)/kT} + 1}$$
 
 Simplification: