Published online by Cambridge University Press: 26 February 2011
We have observed several steps in the I-V characteristics of nonmetallic Sb doped Si near the metal-nonmetal transition. The steps appear at equal intervals in the bias voltage of the low temperature I-V curve and the intervals in the voltage are independent on magnetic field. Such strongly nonlinear conduction can be explained by neither the Joshphson junction effect nor the Stark ladder effect. We have compared it with tunneling models in order to study a new application to a current or a voltage standard using quantum effect transport.