Photovoltaic action from In_xGa_1-xN p-n junctions with x > 0.2 grown on silicon

In this paper, we report systematic investigation of the structural and electronic properties of GaN and In_xGa_1-xN alloys with x up to 0.31 grown on Si (111) substrate. P-type doping of In_xGa_1-xN using Mg has been achieved consistently with magnesium concentrations up to 10²¹ atoms/cm³. The first results on photovoltaic action in InGaN p-n junctions with ~20% In fraction grown on silicon are also reported. An open circuit voltage (V_oc) of almost 1 V was measured under concentrated (20 x sun) AM1.5G condition. The diode shows the onset of a photoresponse at about 2.6 eV. Relatively low shunt and high series resistance are the key factors limiting performance of the InGaN cells with larger In content.