Structural, Optical and Electrical Properties of Hydrogen-Doped Amorphous GaAs Thin Films

Amorphous GaAs films are deposited on substrates of quartz glass and silicon by rf magnetron sputtering technique in different gas ambient. First, the amorphous structure of the prepared samples is identified by x-ray diffraction. Second, analysis by radial distribution function and pair correlation function method is established to characterize the microstructure of the samples. Then, the content and bond type of hydrogen are analysed using Fourier transform infrared absorption spectroscopy. It is found that the bonded hydrogen content increases with increasing partial pressure P_H of H₂. However, the hydrogen content saturates at P_H> 1×10^-1Pa. Hydrogen addition shifts the optical absorption edge to higher energy, decreases the dark conductivity and improves the photo-sensitivity. The optical gap, dark conductivity and photo-sensitivity of the films are dependent on the bonded hydrogen content. These results demonstrate that hydrogen has obvious passivation effects on rf sputtered amorphous GaAs thin films.