1) Magnesium doped gallium nitride is the first blue-purple LED. It shows light emission at 400 nm. Calculate the energy of its optical band gap. (Planck's constant = 6.62607015x10-34 J.: Speed of light = 3 x 10 m.st) 2) Diamond is a colorless Insulator. However, doping suitable transition metals impurity In diamond glves it color. Explain how with the energy diagram. 3) Quantum dot or quantum well, which one is relatively straight forward to prepare? 4) What are the full names of CMOS and OLED? Marks: 4+4+1+1