Demonstration of a III - Nitride/silicon tandem solar cell

We report on the proof of principle of a III-nitride/silicon tandem solar cell. Photovoltaic activity is demonstrated in a 0.25cm² dual junction solar cell, made of p- and n-type GaN layers which were grown by molecular beam epitaxy (MBE) on a standard n-type Si wafer with an Al doped p-type surface. An open circuit voltage (V_oc) of 2.4V was measured under 1 × sun AM1.5G condition with additional UV laser illumination of the GaN junction. Experiments under various illumination conditions were performed to verify that both junctions are active and working in series. © 2009 The Japan Society of Applied Physics.