Growth and characterization of III-V quantum dots on SI-based substrate

Abstract

This thesis presents a systematic study of InAs quantum dot (QD) growth on Sibased

substrates. Two Si-based platforms were studied, namely the graded Si1-xGex/Si substrate which has a high threading dislocation density (~106cm-2), and the germaniumon- insulator (GeOI) platform which has a lower threading dislocation density (<105cm-2). Using the solid-source molecular beam epitaxy, a defect-free GaAs heteroepitaxy on Ge surface can be obtained by employing the low temperature migration enhanced epitaxy technique. QDs with high dot density were obtained by optimizing the growth parameters, such as the V/III ratio and the growth temperature. The photoluminescence of InAs QDs grown on GeOI showed a single-peak emission at 1.33μm with a line width of 36.3meV at room temperature. The promising optical performance enables the demonstration of the world first InAs QD LED on the GeOI substrate. The edge-emitting ridge waveguide LED structure with a 5-layer-QD active core emits at 1.312μm at 25oC. This is a memorable milestone for the monolithic growth of III-V QDs on a Si-platform.