Dear Khaoula Ghezali ,

The deposition time affects the thickness and the homogeneity of the deposited film. The deposited film will be polycrystalline. Inside the grains the carrier concentration is more or less equals to that of the bulk material. Only the grain boundaries which makes the great effect on the mobility of the material rather than its carrier concentration. The carrier concentration is affected very slightly

by the film thickness except some trapping at the surface of the grains.

Best wishes

Dear Khaoula Ghezali ,

The deposition time affects the thickness and the homogeneity of the deposited film. The deposited film will be polycrystalline. Inside the grains the carrier concentration is more or less equals to that of the bulk material. Only the grain boundaries which makes the great effect on the mobility of the material rather than its carrier concentration. The carrier concentration is affected very slightly

by the film thickness except some trapping at the surface of the grains.

Best wishes

Dear Khaoula Ghezali,

The growth of thin films starts from a nucleation process: when the nuclei reach a critical size, the grains grow rapidly and an additional growth appears. This additional growth may affect the direction and the velocity of thin films formation.

you can refer to:

doi.org/10.1155/2015/350196

and

Manipulation of Carrier Concentration, Crystallite Size and Density in Polycrystalline Anatase TiO2 via AmorphousPhase Medium-Range Atomic Order

Goodluck.