Infrared photoresponse from pn-junction Mg2Si diodes fabricated by thermal diffusion

► Mg2Si pn-junction diode was fabricated on single crystalline Mg2Si substrate by thermal diffusion. ► Current-voltage measurement of the pn-junction diodes showed clear rectifying characteristics at 300 K. ► Mg2Si pn-junction diodes showed clear photoresponsivity with a photon energy threshold of approximately 0.6 eV. ► Thermal diffusion coefficient of Ag in Mg2Si was determined experimentally.