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Columnar Film Growth for Solar and Optical Energy Conversion

IP.com Disclosure Number: IPCOM000087654D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Dreyfus, RW: AUTHOR [+3]

Abstract

Columnar films are generally grown having multiple columns extending transversely from the plane of the substrate on which the films are grown. Such films are useful as detectors of incident energy by use of the transverse thermoelectric effect (R. J. von Gutfeld, Applied Physics Letters 23 (1973) p. 206.) and are also useful for solar energy conversion (J. J. Cuomo et al, Applied Physics Letters 26 (1975) p. 557). In the case of solar energy conversion, substantially larger and more vertical columns are used to trap solar radiation. Principally these are tungsten vapor-grown films. The existing methods for growing columnar films are not fully adequate in that the thermoelectric-effect materials, having advantageous thermopower, do not grow in columns because of their low melt temperature.

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Columnar Film Growth for Solar and Optical Energy Conversion

Columnar films are generally grown having multiple columns extending transversely from the plane of the substrate on which the films are grown. Such films are useful as detectors of incident energy by use of the transverse thermoelectric effect (R. J. von Gutfeld, Applied Physics Letters 23 (1973) p. 206.) and are also useful for solar energy conversion (J. J. Cuomo et al, Applied Physics Letters 26 (1975) p. 557). In the case of solar energy conversion, substantially larger and more vertical columns are used to trap solar radiation. Principally these are tungsten vapor-grown films. The existing methods for growing columnar films are not fully adequate in that the thermoelectric-effect materials, having advantageous thermopower, do not grow in columns because of their low melt temperature. On the other hand, columns used for solar energy conversion require specific dimensions for the column length and column spacing, and this has not been possible to achieve with present vapor-growth techniques.

The present technique allows the growth of columnar films with controlled spacings, and can be used for materials which normally will not grow in a columnar fashion due to their low melt temperature when evaporated. The basic principle is that of a plasma containing, in ionic form, the material to be deposited. The plasma is formed by field emission near the tips of the columns and continues the growth process mainly at the columns only, rather than at the spaces between the columns. Once initiated, the columns act like brush electrodes forming the plasma in t...