|
The influence of the built-in electric field (e.g. several potential barriers, impurity gradients, etc) at presence of external crossed electric and magnetic fields on the level of low-frequency noise is theoretically studied by the use of interrelated Langevin type Boltzmann transport equations for the systems of electrons and phonons for non-degenerate n-type semiconductors. At the first time it is shown that within the context of the proposed problem the built-in field causes origin of separate 1/f-noise component, which, besides the main parameters of semiconductor, depends also on the value of this field. The spectral density of this component by the form is similar to the Hooge's empirical formula. For the parameter analogous to the Hooge parameter α the comparison with experimental data for n-type Si is carried out. It is shown that for range of values of the built-in electric field from 50 to 600 V/m at low temperatures from 77K to 150K, the longitudinal component of the analog of the Hooge parameter varies from 10-6 up to 10-4, which in some cases may exceed corresponding values of the generally observed 1/f-noise. The transversal component of the Hooge parameter analog has square dependence on external magnetic field intensity; even for low temperature region, at values of magnetic field from 50 to 400 A/m it has very low values and varies from 10-15 up to 10-11. Basing on the calculations a physical model describing the origin of built-in component of 1/f-noise is proposed. It explains the mechanism of origin of the additional component and helps to shed light on the origin of the general 1/f-noise.
|
