Papers by Author: R.M. Ramović

Abstract: Electron mobility for the silicon-based devices is one of the most important parameters, which determine the behavior of components. Mobility depends on silicon purity, doping level, presence of lattice defects and electric field in the particular device. These influences are particularly important for the nano-scaled devices since it is much more difficult to control the thickness of the active layer, uniformity of impurity doping and appearance of parasitic bipolar devices and capacitances. We have investigated a relationship between the electron mobility for the silicon based PD (Partially Depleted) SOI (Silicon On Insulator) NMOS (n-type Metal Oxide Semiconductor) Devices and the related kink effect, which appears as a consequence of the charge accumulation at the interface of the Buried Oxide. We relate PD SOI NMOS Device technology parameters to the kink effect and we propose a guiding line for alleviating this effect.

Abstract: The focus of this paper was the investigation and modeling of transport characteristics in a strained SiGe based MOSFET structure, which might be of fundamental importance for the understanding of its operating characteristics. In the investigation, carrier mobility dependence on the lateral and vertical electric field is especially considered. Carrier mobility models for long channel as well as short channel SiGe MOSFETs are also presented. Average effective electric field model is proposed taking into account impact of high electric field effects on the effective channel length. In the final effective carrier mobility model, for the short channel SiGe MOSFETs, serial drain to source resistance is included. At the same time, proposed models are relatively simple. By using the presented model, simulations were performed.

Abstract: Optical properties of bilayer organic light-emitting diodes (OLEDs) based on MEH-PPV (2-methoxy, 5-(2′-ethyl-hexoxy)-1,4-phenylene vinylene) and Alq3 (tris(8-hydroxy-quinolinato) aluminum) are investigated in this paper. Numerical method solving 1D model based on driftdiffusion, continuity and Poisson`s equations extended by boundary conditions in treatment of internal organic interface is applied. The obtained space charge densities were employed in the emissive singlet exciton continuity equation resulting in the singlet exciton distribution and the emission zone profile. Dipole methods were utilized for the simulation of light emission in a layered medium. The electroluminescence (EL) spectra of OLED are considered by taking into account dominant interference effects. The exciton quenching near electrodes, allowing for a dominant nonradiative decay, is treated through effective emission zone narrowing.

Abstract: In this paper a new analytical carrier mobility model of a heterostructure unipolar transistor, High Electron Mobility Transistor (HEMT), is presented. The influence of the two dimensional electron gas confined in a HEMT channel on the device carrier mobility, is considered. The mobility dependence on temperature is also included in the model. Advantages of this model are its simplicity and straightforward implementation. Besides, it promises to be applied to quite different types of HEMTs. The model was tested. The results derived from simulations based on the proposed model are in very good agreement with the already known experimental data and theoretically obtained ones, available in literature.