Blister Formation and Layer Transfer of N-implanted GaAs.

Abstract

In this thesis, the blister formation and layer transfer of GaAs:N nanocomposite layers produced by N-implantation, wafer bonding, and rapid thermal annealing (RTA) of GaAs were investigated. In addition, we examined the electrical and thermal transport properties of GaAs:N nanocomposite layers. To examine blister formation mechanisms, the influence of implantation temperature on blister exfoliation depths, lattice damage depth profiles, and N ion fluences was examined. For implantation temperatures of -196 and 300 ºC, we observed an implantation-temperature-insensitivity of blister formation, in contrast to reports of GaAs:H and Si:H, likely due to the lower GaAs:N ion-matrix diffusivity in comparison to that of GaAs:H or Si:H. These results illustrate the key role of diffusivity on the mechanisms of blister formation. The influence of post-implantation RTA on the surface morphology, electrical properties, and Seebeck coefficient of GaAs:N nanocomposite films was examined for RTA temperatures between 800 and 900 ºC. A transition in surface morphology from circular to predominantly elongated features was observed, and attributed to two distinct delamination behaviors. The influence of implantation and RTA on the free carrier concentration, n, and resistivity, ρ, of GaAs:N(Si) and GaAs:N(Te) was examined. For GaAs:N, ρ follows a log-log dependence on n, independent of the dopant species and RTA conditions. Following implantation plus RTA, decreased n and increased ρ were observed for both dopant types with a more significant increase in ρ for the Te-doped GaAs:N layer. In addition, the Seebeck coefficient of the GaAs:N nanocomposite layer is enhanced in comparison to that of GaAs. Finally, the demonstration and optimization of a new process for simultaneous nanostructuring and layer transfer, termed “ion-cut-synthesis,” is described. Indeed, the low ion-matrix diffusivity of GaAs:N enabled the formation of both nanocrystals and gas bubbles at high temperature. In this technique, N ion implantation, spin-on glass-mediated wafer bonding, and RTA are used to achieve simultaneous nanostructuring and transfer of GaAs:N films to Al2O3 and AlN substrates. We identify the critical role of thermal-expansion coefficient matching on the success of the ion-cut-synthesis process.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/75999/1/rcollino_1.pd