THE INFLUENCE OF HYDROGEN ON THE ELECTRICAL-PROPERTIES OF A-GAAS

The electrical properties of hydrogenated amorphous gallium arsenide prepared by r.f. sputtering have been studied. ConductivitY measurements as a function of T evidence two different behaviours depending on the increasing (heating) or decreasing (cooling) T. Metastable effects are also evidenced at T < 360 K, probably linked to the diffusion of bonded hydrogen in the network. Several conductivity curves show a downward kink at T congruent-to 360 K. The presence of this kink has been explained using a model proposed by Spear and assuming the shift of the conduction band edge as a main contribution to the variation of the mobility gap. The Tauc optical gap, the activation energies of the conductivity and the hydrogen content in the network show a rapid increase when C(H) goes from 0 to 10% in the gas phase.