A Si p-π-n diode with β-FeSi2 particles embedded in the unintentionally doped Si (p-type) was designed for determining the band offset at β-FeSi2-Si heterojunction. When the diode is under forward bias,the electrons injected via the Si np－ junction diffuse to and are confined in the β-FeSi2 particles due to the band offset. The storage charge at theβ-FeSi2-Si heterojunction inversely hamper the further diffusion of electrons,giving rise to the localization of electrons in the p-Si near the Si junction, which prevents them from nonradiative recombination channels. This results in electroluminescence (EL) intensity from both Si and β-FeSi2 quenching slowly up to room temperature. The temperature dependent ratio of EL intensity of β-FeSi2 to Si indicates the loss of electron confinement following thermal excitation model. The conduction band offset between Si and β-FeSi2 is determined to be about 0.2eV.