| Ion implantation at keV energies has become a well-established technique for surface modification of solid materials, especially semiconductors. The technique of MeV ion implantation has attracted considerable attention in recent years as it provides an extension of ion implantation technique with a high potential for interface modification of solid materials and for 3-dimensional electronic device fabrication. Extending the ion energy from keV to MeV provides many advantages in terms of the great ion range for deep implantation and the minimized surface damage for modification of deeply buried layers. It also gives rise to many interesting questions about the mechanism of radiation damage and ion-radiation-induced phase transitions. A comprehensive experimental study, from the fundamental to the practical, has been undertaken to investigate MeV ion irradiation effects in III-V compound semiconductors, especially InP and GaAs, and to explore the possibility of its application to optoelectronic semiconductor device fabrication.; Characterization of implanted samples has been conducted by a variety of analytical techniques, such as NRRA, CRBS, XRC, XTEM, HRTEX, SIMS, and IVC. The results have not only demonstrated the complementary nature of all these techniques but also have given clear pictures about the implant distribution, profiles and microstructures of radiation damage and lattice defects, structural phase transformation, and the build-up of lattice strain, as well as electrical property changes. They have revealed the physical relation among all of the effects and led to a better understanding of physical processes involved in MeV ion implantation into III-V compound semiconductors. It has been discovered that MeV nitrogen ion implantation can create a deeply buried high resistivity layer in n-type InP crystals, similar to the case where MeV oxygen ion implantation generates a semi-insulating layer in GaAs-AlGaAs systems. Application of this technique to the fabrication of GaAs-AlGaAs quantum well laser devices with MeV oxygen ions for the electrical isolation and carrier confinement has resulted in a device with high quantum efficiency, low current threshold, and excellent electrical characteristics.; In this thesis, the experimental studies on MeV ion implanted InP and GaAs are presented. Based on the experimental results obtained, the mechanism of MeV-ion-implantation-induced damage and phase transitions in III-V compound semi-conductors is discussed in terms of electronic spikes and nuclear spikes. A mechanism for ion-implantation-induced lattice strain in III-V compound crystals is also proposed. Finally, an example of the application of MeV ion implantation to semi-conductor laser device fabrication is given. |
