ex4

src/14_doping_and_devices.md

@@ -240,9 +240,12 @@ _add fig Fig. 18.2 from the book_. You may assume that the band gap of the $Al_{
 
 1. Sketch the shape of the potential for electrons and holes
 2. If we want to design a bandgap 0.1$eV$ larger than that of bulk $GaAs$, what size of $L$ do we need?
-3. Calculate the density of state of electron and holes in the quantum well
+3. Write down the Schrödinger's equation for electrons and holes (separating $\bf{k}$ in its three components $k_x$
+, $k_y$ and $k_z$)
 ??? hint
     It is a 2D electron gas with confined levels in the third direction
-4. Why could this structure be more useful as a laser than a normal pn-junction?
-5. What would be the advantage of doping the $Al_{x}Ga_{1−x}As$ compared to the $GaAs$?
+4. Find the eigenvalues
+5. Calculate the density of state of electron and holes in the quantum well
+6. Why could this structure be more useful as a laser than a normal pn-junction?
+7. What would be the advantage of doping the $Al_{x}Ga_{1−x}As$ compared to the $GaAs$?