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

Abstract

Photoluminescence (PL) decay time and its temperature dependence were studied in high-density GaAs/(GaAs) 4(AlAs) 2 quantum wires (QWRs) grown on a (775)B GaAs substrate by molecular beam epitaxy, which are naturally 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 interface. The PL decay time of the (775)B QWRs ( τ QWR) was 430 ps at 18 K, which is about 20% longer than that ( τ QW=360 ps) of a GaAs/(GaAs) 4(AlAs) 2 QW simultaneously grown on a (100) GaAs substrate. τ QWR increased slowly with increasing temperature ( T) as τ QWR=30 T 1/2+290 (ps), while τ QW varied as τ QW=6 T+240 (ps). As a result, τ QWR became shorter than τ 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-dimensional characteristics of the (775)B QWRs.