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The study of the structures based on transition metal oxides in conjunction with conventional semiconductor materials (especially with Si) is a prospective direction of development of film oxide devices — Shottky diodes, p-n diodes, field-effect film transistors.
Vanadium dioxide undergoes a dramatic metal–insulator transition (MIT) at a critical temperature TMI = 68οC. Below TMI VO2 is an n-type semiconductor with band-gap energy of 0.7 eV [1]. Above TMI VO2 exhibits metallic behaviour.
In this work we studied the electrical properties of Si-VO2 heterojunction. Single-crystal n and p type silicon wafers were used as substrates. The investigated structures were prepared by anodic oxidation of thin metallic vanadium film sputtered onto silicon substrate. Pulse laser deposition of VO2 was also used. The anodizing conditions were fitted for the complete oxidation of vanadium films up to the silicon substrate. After the anodizing the amorphous film formed on the silicon surface with stoichiometric composition close to VO2, [2]. Polycrystalline channel of VO2 was formed after electroforming.
Voltage-current characteristics of structure were measured at different frequencies (0.1-10 kHz) and signals: sinusoidal, full- and half-wave sinusoidal. As expected, the rectification (asymmetrical voltage-current characteristic) and dependence of the threshold parameters of switching on the frequency and the signal waveform were observed for the majority of the formed switches with the p-Si—VO2 heterojunction.
This work was supported by Svenska Institutet (Dnr:01370/2006), US CRDF grant (award No. RUX0-000013-PZ-06) and by Ministry of Education of Russian Federation.
[1] J. B. Goodenough // J. Solid State Chem., Vol.3. No.4. 1971. P.490-500.
[2] G.B. Stefanovich, A.L. Pergament, A.A.Velichko, L.A. Stefanovich //J.l of Phys. Cond. Mat. Vol.16. No.23. 2004. P.4013-4024.
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