Defect-enhanced interdiffusion at the InGaAs/InAlAs interface due to Si ion implantation

Abstract

Interdiffusion at the InGaAs/InAlAs interfaces which are implanted with Si ions has been studied. Quantum well (QW) structures are grown on InP(Fe) substrates by metalorganic vapor phase epitaxy. Each sample has three InGaAs wells of 2.6, 5.9, and 17.6 nm in thickness and is separated by 24-nm-thick InAlAs barrier layers with each other. The samples are implanted with Si ions at uniform Si densities ranging from 1.8×1017 to 3.9×1019 cm−3 over the QWs, and then annealed under various annealing conditions. The photoluminescence (PL) peak energy from each well is monitored to study the intermixing at the interface. Blue shifts in the PL peak energy are found to occur almost in the early stage of thermal annealing (within 15 s) above the critical Si dose of 2–3×1018 cm−3. The saturated value of the energy shift is determined mostly by the Si density but hardly dependent on the annealing temperature and time. It is concluded that defects formed by Si ion implantation enhance the thermal interdiffusion of Ga and Al atoms at the InGaAs/InAlAs interface, which finishes when implantation-induced defects are annealed out.