R.M. Ramović

HEMT Carrier Mobility Analytical Model

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.

Analytical model of a Si TFT with cylindrical source and drain

In this paper a new analytical model of a silicon thin film transistor (Si TFT) with cylindrical source and drain, is presented. In first part of the text, some basic TFT characteristics and possible applications are exposed. Analytical model is developed starting from Poissons equation, and current density dependence on electric field and voltage. Development of conductivity model follows and finally current-voltage characteristics model. Improvement of the I-V characteristics model is achieved by developing carrier mobility model which is incorporate in it.

Modeling and Investigation of SiGe Based MOSFET Structure Transport Characteristics

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.

N-Type Silicon Electron Mobility and its Relationship to the Kink Effect for Nano-Scaled SOI NMOS Devices

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.

A New Threshold Voltage Analytical Model of Strained Si/SiGe MOSFET

In this paper a new analytical threshold voltage model of a strained Si/SiGe MOSFET is presented. Developed model includes all relevant parameters and it is very precise. Besides the previously mentioned fact and the fact that exposed model describes complex physical processes, the model is relatively simple and easily applicable. Presented model is modular, thus it can be easily observed, tested and eventually improved. This model can be used for strained Si/SiGe MOSFET parameters optimization. By using the proposed model, simulations were performed. Obtained results are in very good agreement with the already known ones

Optical Properties of Simple Bilayer Polymer Light Emitting Diode

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.