Polarization-induced hole doping for long-wavelength In-rich InGaN solar cells

Abstract

The lack of high-quality In-rich p-type InGaN restricts the development of high-efficiency InGaN solar cells toward the whole solar spectrum. In this work, we report a polarization-induced (PI) hole doping method for In-rich InGaN by using the In composition graded p-type InGaN layer with lightly Mg doping. The hole mobility as high as ∼40 cm2/V s is obtained, which is more than ten time higher than that of the single-layer p-type InGaN with the same average In mole fraction. The In-rich InxGa1−xN (x ∼ 0.4) solar cell with the PI doped p-type InGaN exhibits a peak absorption at the wavelength as long as 594 nm. As a result, the conversion efficiency of InGaN solar cell is improved by over 1.5 times compared to that with single-layer p-type InGaN.