The specification describes an improved III-V compound solar cell structure and fabrication process therefor wherein a P-type layer of gallium aluminum arsenide is epitaxially grown on an N-type gallium arsenide substrate to form a P-type region and a PN junction in the substrate. Controlled amounts of beryllium are introduced into both the epitaxial layer and the substrate, either during epitaxial growth or by using beryllium ion implantation techniques subsequent to the P-type epitaxial growth step. The homojunction-heterostructure device thus formed exhibits improved power conversion efficiencies in excess of 17%.
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