FINAL-STATE EXCITATIONS IN THE PHOTOLUMINESCENCE SPECTRA OF INXGA1-XAS-INP QUANTUM-WELLS AT LOW AND HIGH CARRIER DENSITY

Longitudinal-optic (LO) phonon and Fermi-sea shake-up excitations are studied in the magnetooptical spectra of InxGa1-xAs-InP quantum wells. The final-state excitations are observed as low-energy satellites in photoluminescence spectra in magnetic fields up to 20 T. Clear resonan t interactions between the LO-phonon and shake-up satellites are obser ved. In the low-density sample (n(5)=1.15X10(11) cm(-2)) studied, inte raction between the shake-up satellite, corresponding to promotion of an electron from the N-e=0 to the N-e=1 Landau level, and the LO-phono n satellite of the N-e=0 Landau-level transition, is observed. The oth er two samples investigated have high carrier density of 9.2X10(11) cm (-2); one sample has strong disorder and strong hole localization and the other weak disorder and weak hole localization. The sample with st rong hole localization exhibits a Fermi-energy-edge singularity in its photoluminescence (PL) spectrum at zero magnetic field, and has stron g phonon and shake-up satellites. The other high-density sample has a very weak PL signal at the Fermi energy and phonon and shake-up satell ites at high field at least an order of magnitude weaker than in the s ample with strong hole localization. This behavior arises since the st rength of the Fermi edge singularity and the coupling to the LO phonon and shake-up excitations both depend on the degree of hole localizati on in the system. In addition to resonant interaction between the LO-p honon and shake-up satellites, interaction of the phonon satellites of partially filled Landau levels with the N-k=0 electron to N-h=0 hole recombination line is reported. A marked variation of the intensities of these satellites with magnetic field is observed. It is suggested t hat the variation of Landau-level filling with field plays an importan t role in determining the intensities of these satellites of partially filled Landau levels. A theoretical treatment that explains the varia tion of the intensities of the shake-up satellites with field, at low magnetic field in the low-density sample, is also presented.