Enhanced performance of InGaN solar cell by using a super-thin AlN interlayer

A super-thin AlN layer is inserted between the intrinsic InGaN and p-InGaN in the InGaN solar cell structure to improve the photovoltaic property. The dark current is markedly decreased by more than two orders of magnitude and the short-circuit current density is increased from 0.77 mA/cm2 to 1.25 mA/cm2, leading to a doubled conversion efficiency compared to the conventional structure. Electrical transport analysis reveals that the forward electrical property is greatly improved in the range of open circuit voltage and the leakage current mechanism changes from defect related Poole-Frenkel emission to interface tunneling emission. The improvement on the electrical and photovoltaic properties is ascribed to insertion of the AlN interlayer, which not only provides a barrier to reduce tunneling for electrons, but also suppresses the nonradiative recombination. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3654155]