Linewidth enhancement factor of lattice-matched InGaNAs/GaAs quantum wells

The linewidth enhancement factors of lattice-matched 1.5 mum wavelength InGaNAs/GaAs and InGaAs/InP single-quantum-well structures are calculated using microscopic theory and 10x10 effective-mass Hamiltonian. InGaNAs/GaAs quantum wells have a lower threshold carrier density and higher differential gain resulting in a lower linewidth enhancement factor compared with InGaAs/InP quantum wells. For applications which require high gain and carrier densities, InGaNAs/GaAs quantum wells have a much lower linewidth enhancement factor over a temperature range 300-400 K. This lower value originates from the large electron effective mass caused by the nitrogen incorporation. The linewidth enhancement factor of InGaNAs is almost clamped as a function of carrier density and temperature compared with InGaAs. This effect is due to the enhanced match between conduction-valence band density of states and the improved electron confinement caused by the large conduction band offset and deep quantum wells. (C) 2003 American Institute of Physics.