Abstract
There has been great interest in using ion implantation for III-V semiconductor device isolation as an alternative to mesa isolation technique. This is attributed to several advantages that implant isolation has over mesa isolation. Mesa isolation exhibits problems such as over/under etching, repeatability issue of etching depth and nonplanarity of the surface of the semiconductor. However implant isolation is advantageous as the surface planarity is maintained and in general, less intrusion under the mask edges is observed. This thesis presents a study on the isolation of both n and p-type InP and InGaAs layers and n-type InGaAsP layers by ion implantation. Several different ion species such as protons, helium, nitrogen and iron were used to isolate these materials. The n and p-type layers were grown by Solid Source Molecular Beam Epitaxy. Conductive n-type InP layers were also formed using multiple energy silicon implantation to create a uniform dopant distribution throughout the n-type region. The effects of ion mass, implantation temperature, damage accumulation, initial carrier concentration of the conductive layer and post-implant annealing temperature were investigated in detail through electrical and structural characterisation. The major part of the work was to develop recipes for the isolation of the individual InP, InGaAs and InGaAsP layers. The effects of implantation temperature and dose were also examined thoroughly. A parallel resistor model was also created to confirm the reliability of the measurements.