Effect of gamma ray irradiation on the conduction mechanisms of radio-frequency-sputtered Ta/sub 2/O/sub 5/ films

The microstructural and electrical conduction properties of sputtered Ta/sub 2/O/sub 5/ films pre-irradiated and /spl gamma/-ray-irradiated were systematically investigated. Analytical results revealed that the crystallinity and the leakage current of the pre-irradiated sample were effectively improved by raising the irradiation dose at low doses of irradiation [1 M/spl sim/4 M rad(Ta/sub 2/O/sub 5/)]; however higher doses of /spl gamma/-ray irradiation [>4 M rad(Ta/sub 2/O/sub 5/)] undesirably deteriorated the film crystallinity, yielding a larger leakage current. Such a result leads the Frenkel-Poole conduction (pre-irradiated sample) transformed to Schottky emission conduction process [low doses (1 M/spl sim/4 M rad(Ta/sub 2/O/sub 5/)) of /spl gamma/-ray-irradiated samples] and then gradually to the Frenkel-Poole conduction [high doses (>4 M rad(Ta/sub 2/O/sub 5/)) of /spl gamma/-ray-irradiated samples] again.