Browse Prior Art Database

Cumulative Photovoltaic Device

IP.com Disclosure Number: IPCOM000096994D
Original Publication Date: 1962-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Fowler, AB: AUTHOR

Abstract

It is possible with vapor-transport techniques to grow germanium, silicon and other semiconductors in thin layers. If acceptor impurities and donor impurities are added sequentially, alternate n and p regions in thin lamina are obtained. When illuminated from the edge, the P-N junctions produce photovoltages, but the voltages obtained at these junctions tend to cancel in pairs since an N-P junction is followed by a P-N junction. As a result, high values for V are not attainable.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 94% of the total text.

Page 1 of 2

Cumulative Photovoltaic Device

It is possible with vapor-transport techniques to grow germanium, silicon and other semiconductors in thin layers. If acceptor impurities and donor impurities are added sequentially, alternate n and p regions in thin lamina are obtained. When illuminated from the edge, the P-N junctions produce photovoltages, but the voltages obtained at these junctions tend to cancel in pairs since an N-P junction is followed by a P-N junction. As a result, high values for V are not attainable.

By a technique, such as evaporation, a recombination-inducing impurity such as copper, nickel, or some other suitable impurity, is introduced at alternate junctions 1, 2...n. The photovoltaic effect at the alternate junctions is drastically reduced and the device is capable of producing high voltages, since cancellation no longer occurs.

If copper is used in germanium, the thickness of the successive regions is limited by the diffusion length of the copper at 400 degrees C, a typical deposition temperature. The diffusion length is given by, L = sqrt Dt ~ sqrt(10/-8/ * 10/4/) ~ 10/-2/ cm. Thus, only about one hundred junctions are grown in a centimeter and voltages of only 10 volts or so are attained. However, if the recombination-inducing impurity has a lower diffusion constant, as do some of the transition elements, as many as 10/4/ junctions are grown in a centimeter and 10/3/ volts are obtainable in sunlight. The internal resistance of such a device is le...