In a compound $\mathrm{Al}_{*} \mathrm{Ga}_{1 \cdot \mathrm{x}}$ As material, calculate the energy band gap for the $\mathrm{AL}$ concentration of $0.40$ using linear interpolation method at $300 \mathrm{~K}$ temperature. Calculate the minimum carrier concentration $\mathrm{n}=\mathrm{p}$ for population inversion in AlGaAs at $300 \mathrm{~K}$ if the intrinsic carrier concentration is $2.1 \times 10^{3} / \mathrm{cm}^{3}$