Slavik V. Melkonyan

Theory of 1f noise in medium and far infrared photodetectors

Abstract The present report is denoted to the theory of infrared photodiode low frequency noise based on homogeneous and nondegenerate semiconductors. The results of the theoretical calculation are extended to include photodiodes made of elementary semiconductors, as well as of chalcogenides and solid solutions band structures which are described through a two-band Kane model. The kinetic equations of Boltzmann for the system of electrons and phonons are used to calculate the spectral density noise. In the calculation, only the electron-phonon interactions have been taken into consideration. For low frequency noise spectrum an expression is obtained which is well matched with the experimental formula Hooge.

1/f ‐ type Noise in View of Phonons Interface Percolation Dynamics

The influence of long‐wave acoustic longitudinal‐phonon percolation dynamics on 1/f ‐type noise level is modeled for homogeneous, non‐degenerated and bounded semiconductors. Phonons percolation from semiconductor media to environment regions via so‐called «refraction points» of phonons’ wave vector phase space is modeled within framework of the bulk mechanism of electron lattice mobility fluctuation. On the base of this mechanism it is shown, that semiconductor surface is the source of suppression of 1/f‐noise. It is indicated that in some certain applications of the Fluctuation Theory it is physically correct to use Schonfeld model to consider 1/f noises in semiconductors.

Current carrier mobility fluctuations in homogeneous semiconductors

The two main causes of origin of the mobility fluctuation of the electrons in homogeneous, unlimited, and non-degenerated semiconductors are discussed. It is shown that the mobility fluctuation is conditioned by the symmetric component of the fluctuation of the distribution function, i.e. by the fluctuations of the conduction electrons energy. On the base of the developed quasi-classical model the spectrum of electrons lattice mobility fluctuations is calculated. In the frequency wide variation range it has 1/f form.

Slow damping of electron distribution function fluctuations in equilibrium semiconductors

Process of the origin and relaxation of the fluctuation of distribution function of conduction electrons in space-homogenous and non-degenerate equilibrium semiconductors is discussed. The fluctuations of electron distribution function, formed as result of the internal fluctuations of the phonon system, are studied. The physical mechanisms of the origin and following slow (diffusion) damping of the equilibrium fluctuations of the electron and phonon distribution functions are represented. It is shown that in low frequency region the Fourier-component of distribution function fluctuations of predominantly long wavelength electrons and phonons are depends on frequency by law ω-1/2.

Current 1/f fluctuations in equilibrium semiconductor

The current internal fluctuations appearing in the homogeneous, unlimited and non-degenerate semiconductors having parabolic band structure are investigated. At the considered case the external electric field is absent and the semiconductor is in thermal equilibrium state. For the definiteness only the behavior of the conduction electron system is considered. It is shown that equilibrium fluctuations of the electron current, conditioned by the fluctuations of the electron quasi-momentum, are describing by fluctuations of the asymmetric component of the electron distribution function. The following mechanism of these fluctuations is suggested. During the random phonon-phonon scattering the fluctuations of the quasi-momentum of acoustic phonons are coming into existence, which are transmitting to the electron system via electron-phonon interactions. On the base of this mechanism, the spectral density of the electron current equilibrium fluctuations SI(ω) is calculated. It is shown that SI ≈ const in the frequency range ω < ω0. In the frequency range ω>0 < ω < ω1, frequency dependence of spectrum SI(ω) described by 1/ω law, and in the range ω > ω1 it is described by 1/ω2 law. The characteristic frequencies ω1 and ω0 are determined by parameters of semiconductors being under investigation as well as by processes of scattering and diffusion of electrons and phonons in quasi-momentum space.

Electron mobility variance in the presence of an electric field

The influence of an external uniform electric field on electron mobility variance in non-degenerate n-type semiconductor is discussed. Analyzing the result of mobility fluctuation theory, according to which electron mobility variance in equilibrium semiconductor equals infinity, it is shown that in the presence of uniform electric field mobility variance becomes finite. The effect is explained in terms of the so-called electron-phonon FIT (field-induced tunnel) scattering. The results of numerical calculations of mobility variance dependence on electric field are presented for silicon and germanium. It is revealed that mobility variance decreases with the electric field increase by logarithmic law.

Semiconductor‐metal Interface as 1/f Noise Level Regulator

It is demonstrated that by regulating dynamics of the surface and interface losses of phonons it is possible to regulate 1/f noise level in a semiconductor device. On the base of mobility fluctuations phonon mechanism it is shown, that semiconductor‐ metal interface can be considered as potential source of reduction and regulation of 1/f‐noise level.

Noise in p+nn+ structures based on semiconductor compensated by doubly charged acceptors

The results are presented of a theoretical calculation of the spectra of generation-recombination and diffusion noise in p+nn+ structures whose base region is compensated by an impurity that creates doubly charged deep acceptor centers. The results of experimental studies of noise processes in such structures are provided. The theoretical results are compared with the experimental data.