PHONON-ASSISTED RECOMBINATION AND STIMULATED-EMISSION IN MULTIPLE QUANTUM-WELL MO-CVD ALXGA1-XAS-GAAS HETEROSTRUCTURES (LZ-APPROXIMATELY-50A, E1-1'-2XHBAROMEGALO APPROXIMATELY-LESS-THAN HBAR OMEGA LESS-THAN-EL)

Data are presented on two different photopumped multiple quantum-well AlxGa1-xAs-GaAs heterostructures showing that for a large enough number (6) of coupled GaAs quantum wells (Lz {reversed tilde} 50 A ̊) laser operation occurs two LO phonons (2× h {combining short stroke overlay}ωLO) below the lowest confined-particle transitions (E1 or E1'), and for a small number of wells (2) at multiples of h{stroke}ωLO in the {reversed tilde} 240 meV range from just below the L band edge to E1 - h {combining short stroke overlay}ωLO. It is argued that the strength of the electron-phonon interaction is enhanced in two dimensions and that the LO phonon number density Nq is upset (increased) in these quantum well heterostructures, which are grown by metalorganic chemical vapor deposition (MO-CVD). © 1979.