Suppose the heavily doped p-GaAs described above is now sandwiched between AIAs barrier layers to form a single quantum well (SQW) structure with a well width, L= 100 nm. Once again assume for simplicity that the quasi-Fermi level for holes is degenerate with the lowest possible energy level for holes and that the hole concentration is not significantly affected by optical pumping. By considering only the lowest quantized energy level for electron and ignoring any higher energy levels, calculate the minimum photo-generated electron concentration for net stimulated emission by using the 2D density of states for an SQW with L = 100 nm. Give your answer in unit of cm. Answers within 5% error will be considered correct.