Greenʹs function theory of free electrons in thin films

The electronic subsystem of ultrathin films was analysed using Greenʹs function method including quantum size effect and the effect of boundaries to Hamiltonian parameters. Diagonal components of Greenʹs functions were evaluated which enabled a complete insight into the thermodynamical properties of electrons. A comparison with crystal bulk has shown that electronic properties of the materials are strongly influenced both by the sample dimensions and boundary conditions. The numerical calculations show that the electron distribution may be manipulated by varying the surface parameters which is significant for the operation of devices based on thin films.