III-V Molecular Beam Epitaxy Structures for Electronic and Optoelectronic Applications

Citation

Smith, John Stephen (1986) III-V Molecular Beam Epitaxy Structures for Electronic and Optoelectronic Applications. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/r489-8025. https://resolver.caltech.edu/CaltechETD:etd-03082008-083912

Abstract

Molecular beam epitaxy (MBE), a method for depositing epitaxial semiconductor layers with an extreme degree of control, has previously been limited largely to featureless substrates. This thesis describes a procedure for high quality MBE growth over finely patterned GaAs substrates, which is suitable for device fabrication requiring lateral definition of small (~ 1-2 micron) dimension. The results of series of experiments determining the characteristics of MBE growth over patterned substrates are presented. Temperature and flux ratio dependence of faceting during MBE growth over patterned substrates is shown for temperatures ranging from 580° C to 700° C and for As/Ga flux ratios from 1.4:1 to 4:1, and surface diffusion lengths for gallium are measured. The (811) and (411) facets are shown to have growth rates which are at a local maximum and minimum, respectively, for facets tilted in the [01̅1] direction, and implications with respect to other experiments on the atomic growth kinetics on (100) facets are discussed. The material grown over facets tilted in the [0111 direction is shown to be of high quality, with electroluminescence equal to that over the (100) plane.

This method was used for the fabrication of an index guided laser structure, with an optical guide similar to that of the liquid phase grown channeled substrate planer laser structure, as well as tightly packed arrays of these lasers. Yields of individual lasers exceeded 90 percent, and thresholds were uniform to 10 percent. Other potential applications for this technique include a vertical structure high electron mobility transistor, formation of "quantum wire" structures, and methods of directly contacting quantum well layers for device applications and research purposes.

Certain aspects of transport of hot electrons over quantum wells are discussed, with application to several types of devices, including a new type of infrared detector structure, a solid state electron multipler, and a proposed quantum well base transistor.

Thesis Files