Selection of Semiconductors for Tandem Solar Cell Systems

SELECTION OF SEMICONDUCTORS FOR TANDEM SOLAR CELL SYSTEMS 

The range of bandgaps available can be expanded considerably by adopting a concept introduced by Coleman, Holonyak etal [18] 

An analogous procedure has been applied to the copper ternary system by the group at Brown University [ 7-9 ]. This results in five element alloys like example, 

Iso-lattice constant, iso-energy gap and iso-electron affinity maps can be constructed for such alloy systems according to the following procedure developed by Moon etal. Suppose that the values of lattice constant, energy gap and electron affinity are known for the particular ternary alloy represented by the point (x, y ) on the square shown in Fig. 10. Then the values of these parameters for alloys represented by a point (x,y) in the vicinity of (x, y )can be represented by a two-dimensional Taylor series around the point (x, y ) of the form 

If we retain only linear terms, the lattice constant a variation assumes the form (Vegard s law) 

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IV. SELECTION OF SEMICONDUCTORS FOR TANDEM SOLAR CELL SYSTEMS... 

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