The impact of piezoelectric polarization and nonradiative recombination on the performance of (0001) face GaN/InGaN photovoltaic devices

The impact of piezoelectric polarization and nonradiative recombination on the short-circuit current densities (J(sc)) of (0001) face GaN/InGaN photovoltaic devices is demonstrated. P-i-n diodes consisting of 170 nm thick intrinsic In0.09Ga0.91N layers sandwiched by GaN layers exhibit low J(sc)similar to 40 mu A/cm(2). The piezoelectric polarization at the GaN/InGaN heterointerfaces creates drift currents opposite in direction needed for efficient carrier collection. Also, nonradiative recombination centers produce short carrier lifetimes, limiting J(sc). Alternative structures with intrinsic InGaN layers sandwiched by n-type InGaN or graded InyGa1-yN (y=0-0.09) layer and a p-type In0.015Ga0.985N layer have favorable potentials, longer carrier lifetimes, and improve J(sc) to similar to 0.40 mA/cm(2).