Based on the photoluminescence spectrum of Fig. 18.15: (a) Estimate the Al mole fraction (x) in the

Question:

Based on the photoluminescence spectrum of Fig. 18.15:

(a) Estimate the Al mole fraction (x) in the Al_xGa_1-xN layer. Assume that Vegard’s law holds for the calculation of the bandgap energy of the ternary Al_xGa_1-xN from the binary compounds GaN (E_g = 3.4 eV) and AlN (E_g = 6 eV).

(b) Assuming that the defect-related emission peak arises from the transitions from the valence band to a deep level, estimate how deep into the bandgap this deep level rests with respect to the conduction band edge (Δ_E = E_C - E_D).