Study of insulating electrical conductivity in hydrogenated amorphous silicon–nickel alloys at very low temperature

On the insulating side of the metal–insulator transition (MIT), the study of the effect of low temperatures T on the electrical transport in amorphous silicon–nickel alloys a-Si1−yNiy:H exhibits that the electrical conductivity follows, at the beginning, the Efros–Shklovskii Variable Range Hopping regime (ES VRH) with T−1/2. This behaviour showed that long range electron–electron interaction reduces the Density Of State of carriers (DOS) at the Fermi level and creates the Coulomb gap (CG). For T higher than a critical value of temperature TC, we obtained the Mott Variable Range Hopping regime with T−1/4, indicating that the DOS becomes almost constant in the vicinity of the Fermi level. The critical temperature TC decreases with the content of nickel in the alloys.