A forward S-type bistability was observed in a Si diode with two double δ-doped Si tunnel junctions between the p and n contacts. The conductivity in the two branches of the bistable I–V curve changes by seven orders of magnitude. This, coupled with the all-silicon nature of the device, makes it a very attractive multistate device for practical applications. The bistability is explained by a mechanism, referred to as “band switching,” which is supported by temperature dependence of the I–V characteristics.