Characterization of the electrical properties of semimetallic Bi films by electrical field effect

The electrical field effect (EFE) was used to investigate and to characterize the electrical properties of Bi films. The samples were prepared in a capacitor configuration with Al as the gate electrode, Al2O3 as the dielectric and the thin (similar to 1300 Angstrom) thermal-evaporation deposited Bi film sample serving as the other electrode. The dependence of EFE on the electrical field (up to electrical displacements similar to 10(7) V/cm or approximate to 10(13)[e]/cm(2) ''surface'' charge) and on temperature (15-300 K), and also the temperature dependence of Hall constant, were determined. The experimental results are shown to be consistent with the EFE theory of a semimetal film, assuming: that: (1) the film has an interface ''dead layer'' (similar to 600 Angstrom) that does not contribute markedly to EFE due to its extremely low carrier mobilities. Only in the rest, ''good'' part of the film, the electroconductivity is modulated and leads to a measurable EFE; (2) the temperature behavior of EFE follows the temperature dependence of the electron and hole mobilities and its sign is determined by their relative magnitudes. (C) 1997 American Institute of Physics.