Electrical and photoelectric properties of $\alpha$-Si/SiO$_{2}$ and $\alpha$-Ge/SiO$_{2}$ multilayer nanostructures on $p$-Si substrates annealed at various temperatures

The properties of multilayer $\alpha$-Si(Ge)/SiO$_2$ nanostructures deposited onto $p$-Si substrates and annealed at various temperatures are investigated. The total nanolayer thickness is no larger than 300–350 nm. It is found that despite the formation of crystals in a nanolayer, the quantum-size effect does not manifest itself in the photoelectric properties of the nanolayer–substrate heterojunction in the studied temperature range of 300–900 nm. At the same time, the photocurrent efficiency (A/W) in this range becomes constant. The found results are explained by a small nanolayer thickness. When applying a sufficiently large lock bias, the electric field of the nanolayer–substrate junction reaches the outer nanolayer boundary, which abruptly decreases the surface carrier recombination. Just this recombination usually suppresses the photodetector sensitivity in the short-wavelength spectral region. The constant efficiency of the studied heterostructures in a broad spectral range makes them attractive for use in various photoelectric devices.