Electrical conduction in thin metallic, dielectric and metallic-dielectric films

Abstract

Contents 1. Introduction . 1.1. General . 1.2. Structure . 2. Continuous metal films , 2.1. Introduction . 2.2. The theory of thin-film conduction in metals 2.3. Experimental measurements . 2.4. Practical applications . 3.1. Introduction . 3.2. D C conduction mechanisms . 3.3. Breakdown . 3.4. AC conduction mechanisms . 3.5. Temperature coefficient of capacitance 3.6. Preparation . 3.7. Applications . 4. Discontinuous metal films

The transition in hydrogen sensing behavior in noncontinuous palladium films

“…6 However, the characteristics of the interjacent transition regime itself and related changes in electrical response to hydrogen have not been studied yet. Our investigations show that this transition is of a gradual nature and is characterized by a semicontinuous film regime 2,14 that results in characteristic physical properties and distinct responses at H 2 exposure. The semicontinuous state is characterized by the presence of interconnected islands forming continuous metallic pathways isolated by a large fraction of nanogaps ͓see Fig.…”

“…To clearly relate a given R 0 to either a semicontinuous or a discontinuous film type prior to H 2 measurements, we studied the evolution of R 0 with the temperature 14 and after thermal annealing. 1 The temperature coefficient of resistance ͑TCR͒ can give evidence about the electric transport mechanism prevailing within the film.…”

“…1 The temperature coefficient of resistance ͑TCR͒ can give evidence about the electric transport mechanism prevailing within the film. 2,14 In a continuous metallic structure, the increased electron scattering at higher temperatures gives rise to an increase in electrical resistance. 14,21 With the presence of nanogaps, thermally activated quantum tunneling as a transport mechanism comes into play 1 which is characterized by ln͑I / I 0 ͒ ϰ −␦E / ͑k B T͒, where T is the temperature and ␦E is the activation energy.…”

“…2,14 In a continuous metallic structure, the increased electron scattering at higher temperatures gives rise to an increase in electrical resistance. 14,21 With the presence of nanogaps, thermally activated quantum tunneling as a transport mechanism comes into play 1 which is characterized by ln͑I / I 0 ͒ ϰ −␦E / ͑k B T͒, where T is the temperature and ␦E is the activation energy. When a continuous metal film passes into the semicontinuous state the TCR decreases gradually, 14 until a negative TCR is eventually observed where the film becomes discontinuous.…”

“…14,21 With the presence of nanogaps, thermally activated quantum tunneling as a transport mechanism comes into play 1 which is characterized by ln͑I / I 0 ͒ ϰ −␦E / ͑k B T͒, where T is the temperature and ␦E is the activation energy. When a continuous metal film passes into the semicontinuous state the TCR decreases gradually, 14 until a negative TCR is eventually observed where the film becomes discontinuous. Note that electrical transport might occur through the substrate by electron hopping rather than direct tunneling across the air-gaps if these are comparably large.…”