The growth, processing and characterisation of II-VI semiconductor structures

Abstract

The work contained in this thesis focuses on the growth, processing and characterization of II-VI semiconductors for use in opto-electronic devices. Included are efforts to develop both II-VI based distributed Bragg reflectors (DBRs) utilising ZnMgSSe and ZnSe and the epitaxial lift-off (ELO) process pioneered at Heriot-Watt University (HWU). The optical properties of a range of different II-VI compounds (inc. ZnSe, MgS, MnS and ZnMgSSe) are measured using a range of techniques including photoluminescence spectroscopy (PL), optical transmission measurement and spectroscopic ellipsometry. From these measurements, a more accurate value for the bowing parameter of ZnCdSe of 0.37±0.05eV is determined. The effect of lifting structures using an MgS sacrificial layer is investigated by optical microscopy, optical transmission measurement and PL, to allow any structural changes to be determined. The ELO process is also extended to allow structures grown on InP substrates to be lifted by using a magnesium selenide (MgSe) sacrificial layer. The μ-PL measurements of a series of CdSe QDs grown on ZnMgSSe barriers are also reported and compared to previous work on other barrier materials (ZnSe and MgS). The causes of the jitter (spectral diffusion) seen in these samples is also investigated and discussed.