1981-11-19
1984-08-28
James, Andrew J.
357 16, 357 52, 357 61, H01L 2714
Patent
active
044686854
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a semiconductor device and the manufacture thereof; particularly a semiconductor device having a monocrystalline region of semiconductor material in intimate contact with a monocrystalline substrate.
An example of such a device is one including, as semiconductor material, the material gallium arsenide. Regions of this material have been grown epitaxially, both gallium and arsenic, each a metallic material, being deposited in stoichiometric proportion by molecular beams produced in an ultra-high vacuum enclosure. This technique is described in the Journal of Applied Physics Vol 39 p. 4032 (1968) in an article by J. R. Arthur.
BACKGROUND ART
There is inherent in this technique the difficulty of ensuring stoichiometric proportion of the two components. Certainly in order to grow gallium arsenide by this technique it is necessary to supply gallium and arsenic vapors in such a ratio that the collisions between adsorbed gallium and impinging arsenic vapor is equal to the arrival rate of gallium. This requires careful control.
DESCRIPTION OF THE INVENTION
The semiconductor material silicon has also been grown epitaxially from a silicon beam in ultra high vacuum. For many device applications, contacts between metal leads and semiconductor silicon regions are required, particular care being necessary to ensure that such contacts are ohmic. This is a factor having considerable bearing on the economics of mass production of large scale integrated silicon devices where many such contacts are requisite.
Metal material has also been grown epitaxially on semiconductor substrates to provide either conductive contacts or metal Schottky barrier regions. For example, growth of high purity silver, aluminium or gold on indium phosphide has been achieved at growth temperatures of about 30.degree. C., this being the lowest reported temperature for epitaxy of these metals on a III-V compound semi-conductor surface. (CF RFC Farrow et al, Proc 4th Int Conf on Vapour Growth and Epitaxy (ICVGE-4) Nagoya, Japan, July 9-13, 1978, and, RFC Farrow J Phys D, 10 (1977) L135).
Infra-red detectors including one or more regions of the semiconductor material cadmium mercury telluride Cd.sub.x Hg.sub.1-x Te (CMT) are known, and for particular values of the parameter x, eg x=0.21, these semiconductor regions are photo-sensitive to infra-red radiation in the 8 to 14 .mu.m band of the spectrum. Both photo-voltaic and photo-conductive devices of CMT are known.
However, the ternary alloy cadmium mercury telluride is difficult to produce, is relatively expensive, and it is also difficult to produce regions of cadmium mercury telluride with substantial compositional uniformity. It is also a difficult material to incorporate in detector devices, mercury loss readily occurring under extreme temperature and vacuum conditions. Compositional variation leads to variation in the detectivity and spectral response and this can introduce pattern sensitivity in the output response of detector arrays, either linear or 2-dimensional, used in thermal imaging applications. Elaborate corrective circuitry is required to reduce the pattern sensitivity introduced in array output signals.
There is provided, in accordance with one aspect of the invention, a semiconductor device having a monocrystalline region of semiconductor material in intimate contact with a monocrystalline substrate characterised in that the region of semiconductor material is of gray tin stable over a range of temperature in excess of the bulk transition temperature between gray tin and white tin, the substrate being of a material with a crystallographic structure isomorphous with the structure of gray tin, with an interatomic spacing matched to within a tolerance of .+-.17% to the interatomic spacing of the semiconductor material over said range of temperature.
Germanium dopant may be introduced into the tin during the construction of the device, to afford stabilisation of tin layers of thickness greater than .about.0.5 .mu.m. The region therefore may
REFERENCES:
patent: 2865793 (1958-12-01), Nobel
patent: 3615856 (1971-10-01), Sommers
Farrow Robin F. C.
Robertson Daniel S.
James Andrew J.
Mintel W.
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