Study of electrical characteristics of copper oxide films by Hall measurements

Abstract

The electrical characteristics of copper oxide films obtained by the original "in situ CVD" method are studied. The films were synthesized at different times at a temperature of 400 °C in an air-argon mixture using a powdered metal source with a size of 100, 200 or 300 mesh activated by copper monochloride. The thickness of the powder layer was 0.9 mm. Substrates were borosilicate glasses measuring 25x25 mm² with a thickness of 0.17 mm. The measurements were performed by the Van der Pau method using the Ecopia Hall Effect Measurement System (HMS-3000). The thickness of the films was determined by the gravimetric method. The influence of the fractional composition of the powder source and the synthesis time on the electrical characteristics of copper oxide films was studied. To interpret the obtained results, the film samples were studied by optical microphotography and Raman spectroscopy. Hall measurements showed that all samples had a p-type conductivity with (N_A-N_D)=(1-9)E15 cm^-3. For 100 and 200 mesh powders, the concentration of holes initially decreased rapidly with increasing synthesis time, and at a synthesis time of more than 5 minutes, its slow decrease was observed. For 300 mesh powder, the hole concentration remained practically constant at all synthesis times. The study of the mobility dependences on the time of synthesis showed their bell-shaped character. The maximum value of hole mobility equal to 47 cm²B^-1.c^-1 was obtained for Cu₂O films synthesized during a time of 30 min. with 100 mesh powders. The resistivity of the films was weakly dependent on the synthesis time and varied in the range from 100 to 260 Ohm cm, depending on the grain size of the source powder. An explanation of the results obtained by changing the phase composition of copper oxide films is proposed.