The Metal - N-Type Gallium Antimonide (110) Interface: Interfacial Reactions and Schottky Barrier Formation.
Abstract
Available from UMI in association with The British Library. The electrical properties and chemical nature of the interfaces formed, at room temperature, between the (110) surfaces of single crystals of n-type GaSb and a selection of overlayer metals have been investigated. The current-voltage (I-V) measuring technique has been employed to study the influence of different crystalline substrates; surface preparation; and contact metal on the diode characteristics. For all the contact metals (Au, Ag, Al, Cr, Ni, Ga and Sb) the I-V characteristics were observed to be non-ideal and the greatest influence on their appearance has been attributed to the substrate crystal. A smaller dependence on contact metal was also observed, being more readily detected with the most lightly doped crystals (n = 1 times 10^{17} cm ^{-3}) on which the best diode characteristics were obtained. Capacitance-voltage (C -V) measurements were performed but this was only possible for the most lightly doped substrate. Estimates of the effective barrier height for diodes fabricated on both vacuum cleaved and oxidized (110) surfaces were obtained by modelling of the forward bias I-V characteristics, and where possible the C-V characteristics. Ga contacts yielded the highest effective height, however, the closest agreement between the I-V and C-V measuring techniques was observed with the overlayers of Al and Ni. In order to explain the variation in diode behaviour with metal overlayer the reactivity of the interfaces, during the initial stages of Schottky barrier formation, were investigated. For this purpose a combination of synchrotron radiation excited soft X-ray photoemission (SXPS) and conventional X-ray photoemission spectroscopy (XPS), using monochromated Al Kalpha X-rays was employed. These photoemission studies showed that both the vacuum cleaved and oxidized GaSb (110) surfaces were readily dissociated by the deposition of metal overlayers of Au, Ag, Al and Ni, with the selective removal of Sb being observed from the majority of these interfaces. The role of the overlayer growth mode in the disruption of the semiconductor surface and the thermodynamic aspects of these reactiosn were also considered.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1989
- Bibcode:
- 1989PhDT.......169W
- Keywords:
-
- Physics: Condensed Matter