Question

(b) Flgure 3 shows an ideallsed schematic of a PL and PLE spectrum at 4.2K from a GaAs/AIGaAs multi QW (MOW) structure. Assuming the excitation power is low, and assuming the Infinite well approximation, estimate; ü) the width of the well in nm (l) the exciton binding energy in the well With reasoning, state whether thls calculated well width would be an upper or lower limit to the well width in a real GaAs/A GaAs MQW 2] This MQW structure is doped. if the material is high quality what evidence ind cates doping in Flgure 3, and what is the approximate Fermi energy in mev from the bottom of the first confined sub-band of the well? 131 PL PLE 800 805 810 815 Wavelength (nm) Figure 3. Idealised schemotic Pt and PLe spectra from o GaAs/AIGoAs multi quantun well(MQW) structure mo 9.1x10 " kg Rest mass of the electron Electron effective mass (GaAs) m, 0.067 m Heavy hole effective mass (GaAs) me'. O 45 mo. E, (GaAs) (4.2K) 1.519ev

Answer 1

AN SDER Gron that B00 b05 8to BIS oave longh m) t (nm Kert mass <t. elector mo Xto3 E leron effecive mas e oo Heavy hole efectve masa.GaASD mh'-6.45m。 oe l See that Edslale centre ve leri As

B02 5 s 51 ev cilation bindin Eeg e (154766119) ev 0,02866 CV