Anatoly Kovalchuk

A study of the effect of the structure of plasma-chemical silicon nitride on its masking properties

Dependence of the chemical composition of a film of plasma-chemical silicon nitride on the technological parameters of the deposition process is studied. The stages in which the process parameters are optimized in order to improve the masking properties of the film are described. A systematic study of the Fourier-transform infra-red (IR) spectra of plasma-chemical silicon-nitride films is carried out. It is found that the chemical resistance of a silicon-nitride film depends on the configuration in which hydrogen is incorporated into chemical bonds.

Numerical analysis of planar light-emitting diode with designed p-electrode

Light-emitting diode (LED) with designed metal electrode to the top p-semiconductor layer is studied. Original numerical model and procedure are developed for the LED with nonuniform distributions of electrical and optical characteristics caused by the mesh-like configuration of the top electrode. The proposed approach can be used to optimize the LED ouput optical performance by proper choice of the geometrical parameters of the meshed electrode.

Detector for terahertz applications based on a serpentine array of integrated GaAs/InGaAs/AlGaAs-field-effect transistors

Performance of a detector based on AlGaAs/InGaAs/GaAs-material system was studied. The detector was comprised of large serpentine array of high-electron mobility transistors (HEMTs) connected in series. The floating drain contact of each transistor (except the last one) served as a source for the next one. Detection of terahertz (THz) radiation was based on the excitation of electron plasma oscillations in the HEMTs channel. The peculiarities of THz response of the detector in question including an enhanced noise-equivalent power were demonstrated.

Modeling of light-emitting diode with nonuniform current injection

Light-emitting diode (LED) with nonuniform current injection caused by the mesh-like design of top metal electrode is studied numerically. Three-dimensional Laplace equation for electric potential is solved by finite element method. The numerical model incorporates mapped infinite element to account for potential decay far away from the LED structure and finite element model developed for boundary condition at semiconductor-air interface in the mesh opening. Simulation results demonstrate the effect of the mesh geometrical parameters on the total output power.

Modeling of light-emitting diode with top p-electrode patterned as a mesh

Light-emitting diodes (LEDs) with patterned metal electrode to the top p-semiconductor layer resulting in enhanced light extraction are studied. Analytical model which includes an efficient procedure for numerical calculation of light extraction under nonuniform current injection caused by contact patterning is developed and used for modeling of two-dimensional spatial distributions of potential, injected current and output optical power.

Study of fringing effects in multi-cantilever HEMT-based resonant MEMS

An analytical model of a resonant micro-electromechanical system (MEMS) with a high-electron mobility transistor (HEMT)-like structure and an array of resonant cantilevers over its two-dimensional electron gas (2DEG) channel is developed. To account for impact of fringing, spatial distributions of the electric field and sheet electron density at the surface of the HEMT channel are calculated in parametric form. Resistance of the 2DEG channel and frequency-dependent ac amplitude of the source–drain current are derived. The developed model allows evaluation of impact of fringing electric field on output source–drain current for any different number of cantilevers in the array at different spacing between them and can be used for device optimization.