TEMPERATURE-DEPENDENCE OF EXCITON LIFETIMES IN HIGH-DENSITY GAAS (GAAS)(4)(ALAS)(2) QUANTUM WIRES GROWN ON (775)B-ORIENTED GAAS SUBSTRATES BY MOLECULAR-BEAM EPITAXY/

Photoluminescence (PL) decay time and its temperature dependence were studied in high-density GaAs/(GaAs)(4)(AlAs)(2) quantum wires (QWRs) g rown on a (775)B GaAs substrate by molecular beam epitaxy, which are n aturally formed in a 2.1 nm-wide GaAs/(GaAs)(4)(AlAs)(2) quantum well (QW) with a corrugated upper AlAs/GaAs interface (a lateral period of 12 nm and a vertical amplitude of 1.2 nm) and a flat lower GaAs/AlAs i nterface. The PL decay rime of the (775)B QWRs (tau(QWR)) was 430 ps a t 18 K, which is about 20% longer than that (tau(QW =) 360 ps) of a Ga As/(GaAs)(4)(AlAs)(2) QW simultaneously grown on a (100) GaAs substrat e. tau(QWR) increased slowly with increasing temperature (T) as tau(QW R) = 30T(1/2) + 290 (PS), while tau(QW) varied as tau(QW) = 6T + 240 ( ps). As a result, tau(QWR) became shorter than tau(QW) at 50 K. The PL decay time of the (775)B QWRs becomes longer again than that of the ( 100) QW in the rage of 70-80 K. These results suggest good one-dimensi onal characteristics of the (775)B QWRs. (C) 1998 Elsevier Science Ltd . All rights reserved.