X-ray studies of semiconductor device structures.

This dissertation presents the results of high resolution x-ray scattering methods for characterizing the microscopic lattice arrangements of semiconductor device structures. In a new development of this work a new time-resolved x-ray method has been used to probe the kinetics of interfacial strains in such systems. Utilizing synchrotron radiation in conjunction with dispersive optics and fast x-ray area detectors it has been possible to address important questions concerning the evolution of coherent elastic strains in heteroepitaxial layers and their kinetics during rapid thermal annealing. These novel time-dependent x-ray scattering techniques are illustrated with results of rapid thermal annealing effects on strained-layer GaAs-In$\sb{x}$Ga$\sb{1-x}$As-GaAs single quantum well structures, ion-implanted In$\sb{x}$Al$\sb{1-x}$As strained layers and strained Ge$\sb{x}$Si$\sb{1-x}$ layers. High resolution synchrotron radiation measurements of the strain kinetics during rapid thermal annealing show that the lattice strain of an as-grown strained single quantum well is relieved cooperatively by a series of sluggish discontinuous transitions. The results indicate a discontinuous strain behavior in Ge$\sb{x}$Si$\sb{1-x}$ strained layers under rapid thermal conditions when the sample is grown in the metastable regime near its critical thickness. Time-resolved x-ray diffraction data show the presence of two coexisting strain states with a time dependence based on the time rate of change of the temperature. The measurements clearly suggest that cooperative kinetic mechanisms are active and dominant in interface relaxation processes and that the kinetics of single misfit dislocations may not be representative of such dynamic processes as strained-layer relaxation. The new method of probing interface strains in a time-resolved mode has shed new light on the global kinetics of strained-layer structures. The results emphasize the cooperative nature of the relaxation mechanism, involving transitions between partially ordered metastable states of strain. The existence of well-defined, albeit metastable, states of strain in complex multilayered heterostructures may be of practical interest in establishing reliable thermal processing procedures for such systems.PhDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/105884/1/9226886.pdfDescription of 9226886.pdf : Restricted to UM users only