Update 14_doping_and_devices_solutions.md

src/14_doping_and_devices_solutions.md

@@ -37,8 +37,8 @@ Check both cases with lecture notes approximated solutions by doing a Taylor exp
 If all the dopants are ionized, the Fermi level gets shifted up towards the conduction band.
 This result can be obtained when using results in Exercise 1 - Subquestion 2 and the following:
 
-$$ n_D = \approx N_D$$
-$$ n_A = \approx N_A$$
+$$ n_D \approx N_D$$
+$$ n_A \approx N_A$$
 $$ n_e = n_h = n_i $$