ANTI-STOKES PHOTOLUMINESCENCE FROM SI MODULATION-DOPED ALYGA1-YAS ALXGA1-XAS QW AND SI DOUBLE DELTA-DOPED ALXGA1-XAS/

We have observed for the first time band-edge photoluminescence (PL) c orresponding to the quantum well (QW) first subbands transition (simil ar to 1.93 eV) for below-gaps (QWs and barriers) photo-excitation (1.8 -1.92 eV) in Si: modulation doped multiple QWs (MDMQW) in which barrie rs are intentionally doped. In order to unambiguously identify this PL to be anti-Stokes PL (ASPL), the MDMQW structure was selected to be i n the form of 21 Angstrom Al0.2Ga0.8As quantum wells and Si doped Al0. 4Ga0.6As barriers. ASPL observed from MDMQW (1.35 x 10(16) cm(-3) in A l0.4Ga0.6 As barriers) is stronger than bulk Si doped (1.35 x 10(16) c m(-3)) Al(0.4)G(0.6)As taking into account the total number of Si atom s. A similar band-edge photoluminescence (PL) for below-gap photo-exci tation in Si double delta-doped (DDD) (60 Angstrom separation) AlxGa1- xAs(x = 0.35) has been observed. Observation of ASPL at low photon flu ence of 20 W cm(-2) with linear intensity dependence is a clear indica tion of hole generation via below gap one photon excitation. Relativel y strong ASPL is due to the strong hole confinement and combined influ ence of spatial and thermal barriers on electronic occupancy of Si-dee p centers in the barrier. We will describe temperature dependence, dop ing concentration dependence and excitation spectrum of this luminesce nce and correlate its origin to the deep centers within the frame work of small lattice relaxation (SLR) and large lattice relaxation (LLR) models.