Characterization of MG-doped InGaN and InALN alloys grown by MBE for solar applications

InxGa1-xN and InxAl1-xN alloys are grown via MBE on sapphire substrates. A hole concentration of 7.7×10¹⁷ cm⁻³ is achieved on Mg-doped In0.04Ga0.96N. When x≫0.11, the Hall samples exhibit strong n-type polarity, whereas p-type polarity is confirmed by hot probe measurement for all Mg-doped InGaN and InAlN samples. Single p-i-n junction solar cells made of the same InxGa1-xN alloy composition are developed. Upon illumination by a 325 nm laser, Voc is measured at 2.5 V with a fill factor of 61% for all-GaN cell. Clear photo-responses are also observed in InGaN cells with 0.2 and 0.3 Indium content when illuminated by focused outdoor sunlight.