ANOMALOUS ELECTRICAL-CONDUCTION IN SILICON N(-I-N(+) RESISTORS AT LOW-TEMPERATURES())

Charge transport phenomena in n(+)-i-n(+) highly compensated Si resist ors have been investigated in the temperature range 4.2-300 K from mea surements of the I-V static characteristics. The prebreakdown and brea kdown regions of I-V characteristics, observed at liquid-helium temper atures, were simulated by a one-dimensional model including the high c ompensation effect as well as the impact ionization of the frozen-out shallow dopants by the hot electrons injected into the base. An impuri ty hopping conduction mechanism is considered for the prebreakdown reg ime at temperatures between 4.2 and 20 K. Negative differential resist ance (S-type) phenomena are also observed on the I-V characteristics f or high injection current densities and are discussed in terms of the inhomogeneous distribution of the electric field into the base at liqu id-helium temperatures.