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Keywords:

  • InGaN;
  • solar cells;
  • polarization;
  • piezoelectric polarization;
  • p−i−n structures;
  • multi-quantum well structures

Abstract

We performed detailed studies of the effect of polarization on III-nitride solar cells. Spontaneous and piezoelectric polarizations were assessed to determine their impacts upon the open circuit voltages (VOC) in p–i(InGaN)–n and multi-quantum well (MQW) solar cells. We found that the spontaneous polarization in Ga-polar p–i–n solar cells strongly modifies energy band structures and corresponding electric fields in a way that degrades VOC compared to non-polar p–i–n structures. In contrast, we found that piezoelectric polarization in Ga-polar MQW structures does not have a large influence on VOC compared to non-polar MQW structures. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)