CURRENT-VOLTAGE CHARACTERISTICS OF POROUS AMORPHOUS SI1-XMNX IN THE ONE-DIMENSIONAL HOPPING REGIME

We have investigated the temperature dependence of conductivity and cu rrent-voltage (I-V) characteristics of amorphous Si1-xMnx samples (x=4 and 7 at.%) exposed to anodic etching in HF solution, a method used t o produce porous silicon. At low temperatures (T < 38 K) superlinear I -V curves are observed in the voltage range where the unanodized sampl e exhibits Ohmic behaviour. This result is explained in terms of varia ble-range hopping conduction in a network of parallel one-dimensional silicon wires. Carrier mean free paths I = 0.6-1.0 nm and effective ma sses m = (0.4-0.5)m(o) are deduced from the analysis of the experimen tal data.