Update src/14_doping_and_devices.md

src/14_doping_and_devices.md

@@ -256,7 +256,7 @@ Consider a pn-junction diode as follows
 
     By Raffamaiden [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]), [Link](https://commons.wikimedia.org/wiki/File:PN_diode_with_electrical_symbol.svg)
 
-The current generated by the pn diode as a function of applied bias voltage is given by 
+The current flowing through a diode as a function of applied bias voltage is given by 
 
 $$ I(V) = I_s(T)\left(e^{\frac{eV}{kT}}-1\right)$$
 
@@ -264,11 +264,10 @@ where $I_s(T)$ is the current flowing through a diode when it is reverse biased
 
 <Add I-V plot of pn diode from simon's book>
 
-1. Write down two possible scenarios by which a pn diode generates a small current in the reverse biased condition.
-2. How does the temperature affect the diode performance in the two scenarios written in 3.1.
+1. Discuss two possible scenarios by which a pn diode generates current in the reverse biased condition.
+2. How does temperature affect the saturation current $I_s(t)$ in the two possible scenarios? 
 3. Sketch a plot of saturation current as a function of temperature T.
-4. Explain the dominant contribution to current generation in the forward biased condition.
-5. Does two intrinsic semiconductors joined together functions as a diode?
+4. Does two intrinsic semiconductors joined together generates current?
 
 ### Exercise 4: Quantum well heterojunction in detail
 A quantum well is formed from a layer of $GaAs$ of thickness $L$, surrounded by layers of $Al_{x}Ga_{1−x}As$.