Electrical conductivity of p-type CuInSe2 thin films

The dark ohmic conductivity σ(T) of several p-type CuInSe2 thin films of different compositions was measured in vacuum in the temperature range 100–350 K. The room-temperature resistivity of Cu-rich, highly conducting films and the Cu-poor, highly resistive films varied by seven orders of magnitude. For the most conducting films (Cu:In>1, ρ∼0.1 Ω cm), σ(T) was pseudometallic, i.e., dσ/dT≲0. The Cu-poor films exhibited a thermally activated conductivity, i.e., σ(T)=σ0 exp(−E/kT), over a considerable temperature range. The data of post-deposition anneal in air and subsequently in hydrogen are in excellent agreement with Meyer–Neldel type of conduction, i.e., σ(T)=σ00 exp(−E/kT0)exp(E/kT). We attribute this behavior to the compensation of the films by oxygen.