HOT CARRIER DYNAMICS IN GAAS EPILAYER STRUCTURES GROWN ON SI

Picosecond time- and energy-resolved photoluminescence (PL) spectrosco py is used to investigate hot carrier dynamics in GaAs epilayer struct ures grown on silicon substrates. The existence of biaxial stress aris ing from the thermal expansion difference between GaAs and Si substrat es alters the valence band of GaAs epilayer structures on Si. Using th e radiative transitions from electrons in donor (Si, 10(16) cm-3) stat es to separated valence bands in a 2-mu-m GaAs epilayer on Si, energy relaxation of thermalized hot holes is studied. Different electron ene rgy relaxation dynamics are observed in thin and wide modulation Be-do ped GaAs-AlGaAs multiple quantum wells grown on Si substrates, arising from different valence subband structures.