Michael L Crisp

US Patent:

40574768, Nov 8, 1977

Filed:

May 26, 1976

Appl. No.:

5/690344

Inventors:

Esther Krikorian - Claremont CA
Michael J. Crisp - Placentia CA

Assignee:

General Dynamics Corporation - Pomona CA

International Classification:

C23C 1500
H01L 3100

US Classification:

204192P

Abstract:

Photovoltaic diodes prepared by the methods of the invention include p-n (or n-p) heterojunction or homojunction diodes as well as Schottky barrier diodes where both elements of the diode comprise thin monocrystalline films of Pb. sub. 1-x Sn. sub. x Te or a thin monocrystalline film of Pb. sub. 1-x Sn. sub. x Te and an appropriate thin barrier metal film. Such a monocrystalline Pb. sub. 1-x Sn. sub. x Te film is sputter deposited, has a composition Pb. sub. 1-x Sn. sub. x Te which may range from x = 0. 0 to about x = 0. 3 and, consequently, can be preselected to have a photovoltaic response with response cutoff wavelengths ranging from about 6. mu. m to about 25. mu. m at 77. degree. K. The first film is sputter deposited under controlled conditions in accordance with the present method, including at low pressure of selected gas and at selected substrate temperature and film growth rate conditions with or without substrate temperature and film growth rate condition with or without substrate bias voltage of from about +30 volts to about -30 volts, so as to control the composition and stoichiometry of the resulting film as well as its carrier type, carrier concentration and Hall mobility to provide selected electro-optical properties. Thereupon a second film is deposited, which is either a film of composition Pb. sub. 1-x. sbsb. 1 Sn. sub. x. sbsb.

US Patent:

40865550, Apr 25, 1978

Filed:

May 27, 1976

Appl. No.:

5/690463

Inventors:

Esther Krikorian - Claremont CA
Michael J. Crisp - Placentia CA

Assignee:

General Dynamics Corporation - Pomona CA

International Classification:

H01L 3108

US Classification:

338 15

Abstract:

An improved photoconductive sensor is provided which includes a substrate of calcium fluoride or barium fluoride in monocrystalline form upon which has been sputtered under controlled conditions a thin unannealed monocrystalline film having the formula Pb. sub. 1-x Sn. sub. x Te where x = about 0-0. 3. The conditions under which the film is deposited are controlled so that the film exhibits a cutoff wavelength between about 6. mu. m and about 15. mu. m, a photoconductive responsivity which may be as high as up to about 10. sup. 3 V/watt at 77. degree. K and a detectivity peak value which may be as high as up to about 1. 5. times. 10. sup. 10 cm-Hz. sup. 1/2 /watt at frequencies above the 1/f noise frequency. The film also exhibits a fast response time of less than about 100 nanoseconds and is usually present in a thickness, for example about 1-2. mu. m, corresponding to high quantum efficiency and minimal contribution of unexcited film to detector noise.