Mott and Efros-Shklovskii hopping conductions in porous silicon nanostructures

Electrical conductivity of electrochemically etched porous silicon was studied over a wide temperature range from 15 to 450 K. Applicability of various electrical transport mechanisms has been critically analyzed. While the conductivity data above room temperature shows extended state conduction, lowering the temperature leads to Berthelot-type conduction (180–280 K). Further, Mott's hopping (in the range 140–180 K) and Efros-Shklovskii hopping (below 120 K) conduction are found to be operating in lower temperature ranges. A clear crossover from Mott to Efros-Shklovskii variable range hopping transport is observed at low temperatures.