BaSi2 is an emerging material for solar cell applications. We investigate the defect properties of 0.5 mu m thick BaSi2 films by photoresponse and photoluminescence (PL) measurements. The photoresponsivity of BaSi2 films measured under a bias voltage of 0.3 V applied between the front-surface and rear-surface electrodes at room temperature was enhanced by doping B atoms of the order of 10(18) cm(-3). Much further enhancement was achieved after atomic H supply for 5 min by a RF plasma gun. These results suggest that the doping of B and H atoms is an effective means to passivate the defects in BaSi2 films. PL measurements at 8-9 K highlighted the existence of localized states within the bandgap. Measured PL spectra were decomposed into two or four Gaussian curves. The enhancement of photoresponsivity was ascribed to the decrease of deep defect levels. (c) 2020 The Japan Society of Applied Physics