On the measurement of the conductivity density of states of evaporated amorphous silicon films

Data are analyzed on the conductivity across the barrier between amorphous and crystal Si. The analysis assumes that variable range hopping near the Fermi level is the dominant conductivity mechanism in the evaporated amorphous Si film and band conductivity is dominant in the crystal. The density of states is found to be 1.2 × 10²⁰ eV⁻¹ cm⁻³ at the Fermi level in amorphous Si. The barrier heights are found to be larger when the crystal is p‐type. This is in contrast to the somewhat analogous case of metal–semiconductor Schottky barrier diodes in which n‐type crystals give higher barriers. The possibility of applications in circuits is pointed out.