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We consider a model of the stripe Schottky contact with a uniformly doped semiconductor. It is assumed that at the boundary of the semiconductor, the position of the Fermi level is fixed due to the high density of surface states in the band gap. An analytical solution of the problem of the potential distribution, the shape of the depletion region, and the high-frequency capacitance of the contact is found in the full depletion approximation. Based on the approach developed, we study quadratic nonlinear properties of the FET with a Schottky barrier in the high-frequency signal detection mode. [ABSTRACT FROM AUTHOR]

The previously proposed technique of microwave volt–impedance spectroscopy of semiconductors has been experimentally verified. The technique allows one to determine the local values of electrical parameters of a semiconductor. The investigations have been carried out on a homogeneous single-crystal GaAs wafer with a system of concentric antennas formed on the top of it. The resolution is determined by the antenna central disk diameter, which has been 12, 27, and 57 μm. A dc bias voltage of 0 V ≤ U ≤ 5 V has been applied between antenna contact pads. The complex Z(f, U) impedance spectrum of each antenna has been measured on a Cascade Microtech probe station in the frequency range of f = 0.1–10 GHz. The electrical characteristics of the semiconductor have been determined from the Z(f, U) spectra by solving the inverse problem. The n-type of the semiconductor has been established, and the contact potential difference at the interface with a metal has been determined. The local values of electron density, mobility and electrical conductivity have been found have been found. The four-point probe Hall effect measurements of the surface-averaged values of the same parameters have shown good agreement of the results for the investigated homogeneous wafer. [ABSTRACT FROM AUTHOR]

Using a drift-diffusion approximation, we obtain an analytical solution to the problem of charge-carrier injection into an insulating i layer of finite thickness with account of self-consistent boundary conditions. The main assumption is that the self-doping of the i layer is neglected. The solution makes it possible to calculate the potential, electric field, and current-voltage characteristics of a variety of structures such as metal-i layer-n+ (or p+) semiconductor, metal-i layer-metal, and n+(p+)-i-n+(p+) structures. The solution admits a generalization for structures having heterobarriers at the interface of the semiconductor layers. The proposed approach allows for the contact phenomena and bulk effects related to that the current is space charge-limited in the i layer. The solution is valid for both the limiting cases and the transient regimes. [ABSTRACT FROM AUTHOR]

The problem of charge carrier injection into a finite-length insulating layer is analytically solved in the drift-diffusion approximation, taking into account self-consistent boundary conditions. The main assumption is the neglect of intrinsic doping of the i-type layer. The solution allows calculation of the potential, electric field, and current-voltage characteristics of various structures, i.e., metal- i- n + (or p +)-semiconductor, metal- i-layer-metal, and n +( p +)- i- n +( p +) structures. The solution allows generalization for structures having heterobarriers at semiconductor layer interfaces. The proposed approach considers contact phenomena and volume effects associated with the space-charge-limited current in the i-type layer. The solution is valid in both extreme cases and intermediate conditions. [ABSTRACT FROM AUTHOR]

Nonlinear properties of capacitance and frequency dependence of admittance for a multilayer metal-semiconductor structure are studied theoretically. It is shown that admittance of such structure depends on the frequency of a small probe signal. The voltage dependence of capacitance measured using a low-frequency probe signal can be nonmonotonic. The behavior of the structure’s capacitance at a large amplitude of external signal is studied. After some time from the instant of switching-on of the high-frequency signal, the system is found in a steady state with certain charge of the metal layer and predefined capacitance of the system. In the steady state, the charge of metal and the capacitance do not depend on the instantaneous value of the voltage; rather, they are governed by the signal’s amplitude. [ABSTRACT FROM AUTHOR]

Multilayered InAs/GaAs quantum dot (QD) heterostructures are produced by metal-organic gas phase epitaxy. The structures exhibit photoluminescence around 1.55 μm at 300 K. The specific feature of the technology is the growth of an InAs layer with an increased effective thickness d eff to form QDs, in combination with low-temperature overgrowth of the QDs with a thin (6-nm) GaAs layer and with the annelaing of defects. By X-ray diffraction analysis and PL studies, it is shown that, in a structure with the increased thickness d eff, a secondary wetting InGaAs layer is produced on top of the QD layer from the growing relaxed large-sized InAs clusters on annealing. A new mechanism of formation of large-sized QDs characterized by a large “aspect ratio” is suggested. The mechanism involves the 2D–3D transformation of the secondary InGaAs layer in the field of elastic strains in previously formed QDs. The specific feature of the array of QDs is the coexistence of three populations of different-sized QDs responsible for the multimode photoluminescence in the range from 1 to 1.6 μm. The potentialities of such structures for infrared photoelectric detectors operating in the range from 1–2.5 μm at room temperature are analyzed. [ABSTRACT FROM AUTHOR]

It is shown that organometallic vapor-phase epitaxy can be used to form an artificial medium that constitutes a matrix of single-crystal GaAs with incorporated Al nanoparticles. Electrical and optical properties of this medium are studied. [ABSTRACT FROM AUTHOR]

Potential distributions around spherical and cylindrical metallic nanocontacts in semiconductors are calculated. Electrical properties of nanocontacts of small characteristic size a

We have studied the temperature dependence of the Hall effects in multilayer selectively doped InGaAs/GaAs heterostructures with quantum dots (QDs). It was found that structures possessing photoconductivity in the IR range exhibit a sharp (nearly exponential) growth of the conductivity and Hall mobility in the temperature interval from 8 to 30 K at a virtually constant Hall coefficient and electron density. A new mechanism of the lateral photoconductivity in the structures with QDs is proposed which is related to the change in the electron mobility in the two-dimensional channel as a result of a decrease in the Coulomb scattering on charged QDs. [ABSTRACT FROM AUTHOR]

The theory of tunneling current in metal–semiconductor contacts with subsurface isotype δ-doping is developed. Analytical expressions for current that take into account the decrease in the potential barrier height due to the image forces are obtained using the Murphy–Good approach. Characteristics of δ-doping that provide effective thermal field emission at the metal–semiconductor contact and a decrease in the effective barrier height from the original value to several kT are calculated. It is established that the main voltage dependence of the current in a contact with isotype δ-doping is exponential. It is shown that the nonideality factor can remain small (n ≤ 1.07) for all values of the barrier height. A dramatic increase in n to the values n ≥ 1.5 is typical of contacts with a partially depleted layer. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Deals with a study which proposed three methods for determination of a detailed structure of dopant distribution in semiconductors based on the data of electrochemical capacitance-voltage profiling. Basic equations; Approximation of complete depletion of the nonuniform doped region; Method for inverse reconstruction of the doping profile; Results of numerical simulation; Conclusion.

We have studied the room-temperature photoconductivity in the wavelength range 1–2.6 μm in InAs/GaAs heterostructures with quantum dots (QDs). Specific features of these heterostructures grown using the metalorganic vapor phase epitaxy (MOVPE) were an increase in the amount of InAs during the formation of a sheet of QDs and the use of alternating low-and-high-temperature regimes during their overgrowth with a GaAs barrier layer. For the first time, the MOVPE-grown multilayer InAs/GaAs heterostructures with quantum dots exhibited photoluminescence in a wavelength range of up to 1.6 μm and the photoconductivity up to 2.6 μm at room temperature. The heterostructures exhibited a room-temperature voltage sensitivity of 3 × 103 V/W (within a Si-plate filter bandwidth) and a specific detectivity of 9 × 108 cm Hz1/2 W−1. [ABSTRACT FROM AUTHOR]

Metalorganic vapor phase epitaxy (MOVPE) was used to grow semiconductor structures comprising a GaAs single crystal matrix with incorporated layers of aluminum nanoclusters (Al-NCs). A new regime of GaAs overgrowth on Al-NC layers is proposed, which ensures planarization of the semiconductor layer surface at a thickness comparable with the height of Al-NCs. [ABSTRACT FROM AUTHOR]

Specific features in the formation of InAs quantum dots (QD) by MOCVD were studied in relation to the growing time or equivalent thickness of the InAs layer. TEM and photoluminescence studies have shown that, as the growing time of QDs in a GaAs matrix becomes longer, both the size and shape of the QDs are modified; namely, the aspect ratio increases. Selectively doped multilayer InGaAs/GaAs QD structures were fabricated, and photoconductivity in the IR range was studied for lateral and vertical electron transport. Under a normal incidence of light, intraband photoconductivity in the mid-IR range, 2.5-5 μm, was observed at temperatures of up to 110 K. [ABSTRACT FROM AUTHOR]