Browse Prior Art Database

Solar Cell Structures

IP.com Disclosure Number: IPCOM000080348D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Hovel, HJ: AUTHOR [+3]

Abstract

One of the problems associated with the GaAlAs-GaAs solar cell is the difficulty of achieving low-contact resistance to layers containing high Al concentrations. Two structures in which contacting is made on a surface of material other than GaAlAs are described below. In addition, these structures alter other optical and electrical properties in a manner which improves the efficiency of the cell, particularly at Air Mass zero condition. I. Structure with GaAs surface.

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Solar Cell Structures

One of the problems associated with the GaAlAs-GaAs solar cell is the difficulty of achieving low-contact resistance to layers containing high Al concentrations. Two structures in which contacting is made on a surface of material other than GaAlAs are described below. In addition, these structures alter other optical and electrical properties in a manner which improves the efficiency of the cell, particularly at Air Mass zero condition. I. Structure with GaAs surface.

One of the structures is shown in Fig. 1. It is similar to the conventional structure, except that a thin layer of pure p+ GaAs is deposited on GaAlAs window layers prior to the termination of growth. In practice, since this is done by a nonwiping LPE (Liquid Phase Epitaxy) system, another thin layer of GaAlAs ;; AlAs grows on the GaAs during growth termination. This termination layer is etched off with HCl. (Note that if a termination layer grows on the GaAlAs window, an HCl etch would remove both the termination layer and the window layer). The cell is given a Zn diffusion to lower the surface resistance of the GaAs prior to contact.

Next, the GaAs layer is contacted via a blanket layer of evaporated Au-95%, Zn-5%. Next, a photoresist pattern is applied and the unwanted contact material is stripped away. (It could have been alloyed before being stripped away, if desired). Next, the GaAs layer is removed everywhere except under the metal contact pattern using 1:1:2; NH(4)OH:H(...