Abstract. Hybrid structures consisting of an n-Si substrate covered with a cationic polyethylenimine layer and an anionic dye layer were fabricated. Their electrical properties were characterized using tunnel current measurements by a tungsten probe. The obtained I-V curves were analyzed using a modified diode equation. We found out that adsorption of the cationic polyelectrolyte decreases the barrier height of n-Si/organic monolayer/W structure, while adsorption of the low molecular weight anionic dye increases it. The results demonstrate that along with thermionic mechanism other ones are present which prevail at low voltage. In particular, electron tunneling dominates for a single monolayer on the silicon substrate, while, apparently, the Pool-Frenkel mechanism is typical for two monolayers.
IntroductionHybrid structures consisting of organic and inorganic components are a subject of interest in various research fields [1] as they combine well-known and developed inorganic materials with a huge amount of organic ones properties of which can be varied in wide ranges. In particular, such structures based on inorganic semiconductors can be used in microelectronics [2], sensors [3] and photovoltaic applications [4].There are several models describing electron transfer in hybrid structures [2] which defines their electrical properties. Moreover, models of charge transport through organic molecules were also elaborated [5] to estimate electrical properties of hybrid structures with thick organic layers. Therefore, the conduction mechanism for a certain hybrid structure should be considered separately.In the present work we examine the electrical properties of hybrid structures consisting of a silicon substrate covered with a cationic polyelectrolyte monolayer and an anionic dye layer using tunnel current measurements.