Opportunities in dilute nitride III-V semiconductors quantum confined p-i-n solar cells for single carrier resonant tunneling

Stunning theoretical efficiencies have been predicted for quantum-confined solar cells. However, practical realizations remain inefficient as these devices suffer from an inherent difficulty in the extraction of photo-generated carriers from the confined states. Leveraging on the shallow valence band offset of dilute nitrides and using a carefully chosen material system and device design, we show the possibility of circumventing this problem by separating the optimization of the valence and conduction band and reducing the issue to a single particle problem. Band structure calculations including strain effects, band anti-crossing models and transfer matrix methods are used to theoretically demonstrate optimum conditions for enhanced vertical transport. High-electron tunneling escape probability, together with a free movement of quasi-3D holes, is predicted to result in enhanced PV device performance. Furthermore, the increase in electron effective mass due to the incorporation of N translates in enhanced absorptive properties, ideal for PV application. (C) 2008 Elsevier Ltd. All rights reserved.