1. Determine Eg for the different compositions of the AlGaAs alloy.  Indicate if it is a direct band gap or an indirect band gap.
 

2. What physical significance or consequence does the direct or indirect bandgap have (i.e., in terms of the light emission efficiency) ?  Explain !

3. Would the Light Emitting Diodes and Laser Diodes be made from a direct bandgap materials or from the indrect bandgap materials ?
              (a) direct bandgap materials                 (b) indirect bandgap materials

4. Why is the indirect bandgap materials so inefficient compared with the direct gap materials ?  Explain !