EFFECT OF COMPOSITION, THICKNESS AND TEMPERATURE ON NONLINEAR I-V CURVES IN VANADIUM PHOSPHATE-GLASSES

Glass layers of (V2O5)(1-x)(P2O5)(x) were prepared by melting appropri ate mixtures of V2O5 and P2O5 powders. The measurements of I-V charact eristic curves show three regions of conduction, namely high-resistanc e state, turnover point with zero-differential resistance region (part ial derivative V/partial derivative I=0) and differential negative-res istance region. The turnover point is strongly dependent on compositio n, sample thickness and temperature. It is found that the increase of the ratio of phosphorus/vanadium reduces conductance as well as it rai ses the field required to produce turnover behaviour. The data in,the range up to the turnover point are discussed on the basis of an electr othermal process. Results of the negative-resistance state could be ex plained in terms of a hopping mechanism.