Part I. Solid-Phase Growth of Germanium Structures. Part II. Condensation of Injected Electrons and Holes in Germanium

Citation

Marrello, Vincent (1975) Part I. Solid-Phase Growth of Germanium Structures. Part II. Condensation of Injected Electrons and Holes in Germanium. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/56z0-0h91. https://resolver.caltech.edu/CaltechTHESIS:08312021-204039498

Abstract

Part I

Solid-solid reactions between a semiconductor and evaporated metal films can lead to semiconductor crystal growth. In this work, two aspects of solid-phase growth have been investigated; 1) growth of epitaxial Ge layers from a solid solution of Ge in an Al film onto single crystal Ge substrate (solid-phase epitaxy), and 2) growth of Ge crystallites in Al films from amorphous Ge films deposited on the Al film.

In solid-phase epitaxial studies, backscattering measurements with MeV ⁴He⁺ ions showed that a solid-solid reaction occurred at temperatures below the Ge/Al eutectic point. Channeling effect measurements with MeV ⁴He⁺ ions indicated that the Ge layers were well-ordered and epitaxial. Electron microprobe measurements indicated the Ge layers contained Al. Hall effect measurements showed the Ge layers to be heavily p-doped. These Ge layers have been used to construct p-type contacts on p-n diodes, double injection diodes and nuclear particle detectors.

Ge crystallite growth in Al films occurs when an amorphous Ge film is deposited on an Al film and is heated at temperatures below the Ge/Al eutectic point. Crystallization of Ge occurs by an initial dissolution of Ge into the Al film followed by diffusion and growth of Ge crystallites in the Al films.

The nature of Ge crystallite growth has been studied by MeV ⁴He⁺ ion backscattering techniques, transmission electron diffractometry, scanning electron microscopy and electron microprobe analysis.

Part II

We demonstrate for the first time that the condensation of electrons and holes in Ge can be produced by electrical injection of carriers. The condensate occurs in double injection diodes at temperatures of at least up to 5°K.

The recombination radiation from the condensate was analysed using an infrared spectrometer. The LA- and TO-phonon assisted recombination radiation lines from the condensate occur at 709 meV and 700 meV respectively. The linewidth at half maximum of the 709 meV line is 3 meV. We measure a lifetime for the condensate of 40 μs. The radiation was emitted almost uniformly from the volume between the contacts of the double injection diode. The radiation intensity increased with increasing current and decreasing temperature.

LA-phonon assisted exciton and bound exciton recombination radiation lines at 714 meV and 712 meV respectively were observed from 7 to 15°K. Above 15°K, only the exciton line was observed. The recombination radiation lifetime of the exciton at 20°K is 6 μs.

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