Update 14_doping_and_devices_solutions.md

src/14_doping_and_devices_solutions.md

@@ -38,7 +38,7 @@ This result can be obtained when using results in Exercise 1 - Subquestion 2 and
 
 $$ n_D \approx 0$$
 $$ n_A \approx 0$$
-$$ n_e = n_h = n_i $$
+$$ n_e - n_h = N_D - N_A $$
 
 
 ### Subquestion 2
@@ -49,8 +49,9 @@ $\ast$ indicates non-ionized concentrations.
 ### Subquestion 3
 
 ??? hint "how?"
-    Use Germianium Fermi Energy at room temperature and perform the
-    [key algorithm of describing the state of a semiconductor](13_semiconductors/#part-1-pristine-semiconductor)
+    Use Germianium Fermi Energy at room temperature and solve E_F 
+    via using the n_e solution in Exercise 1 and by applying the definition of n_e.
+    Check [key algorithm of describing the state of a semiconductor](13_semiconductors/#part-1-pristine-semiconductor)
 
 ## Exercise 3: Performance of a diode