The photovoltaic performance of a GaN p-n-n homojunction is characterized using the air-mass (AM) 1.5 G solar spectrum and a 532-nm green laser. The n-type active region is doped with Si in order to create an intermediate band for sub-bandgap photon absorption. When the doping level in the active region increases from 0 (unintentionally doped) to n=1 x 10(18) cm(-3), the short-circuit current density (J(SC)) under illumination by the green laser is noticeably reduced, whereas the J(SC) under AM1.5G is significantly enhanced by 90%. The results indicate that the Si-induced intermediate band is partially filled, a key feature favored by intermediate band solar cells. (C) 2014 Elsevier B.V. All rights reserved.