MOVPE growth of thick (similar to 1 mu m) InGaN on AIN/Si substrates for InGaN/Si tandem solar cells

摘要

In order to develop key technologies for InGaN/Si two-junction tandem solar cells, MOVPE growth of thick InGaN on Si p-on-n cell structures has been studied. By clarifying the phase separation behavior of MOVPE InGaN, a thick (similar to 1 mu m) InxGa1-xN (x similar to 0.5) without phase separation is successfully grown on AlN/Si(111) wafers. A sufficient current flow for the operation of the tandem cell is obtained through n-InGaN/AlN/p-Si structures by employing the annealing of AlN/Si wafer at around 1000 degrees C in NH3 flow just before InGaN growth. The annealing of AlN/Si wafers also brings about the degradation of the underlying Si pn junction. The optimization of the annealing conditions is required to balance such favorable and unfavorable effects. (C) 2015 The Japan Society of Applied Physics