Si devices with two double delta-doped tone p-delta and one n-delta) junctions were grown by silicon molecular beam epitaxy (MBE). A new I-V bistability phenomenon was observed in those devices. We used a 'band switching' mechanism to explain the bistability. Devices with different doping and spacer widths were grown to test the proposed mechanism. Finally, a detailed temperature dependence measurement of the I-V characteristics was shown to confirm our proposed mechanism.