Low-dimensional transit-time structures for terahertz generation and detection are discussed. The negative conductivity at terahertz frequencies is crucial for generation. It may arise in an array of silicon nanowires (1D), as well as in a thin silicon layer (2D) in “silicon-on-insulator” wafer. Ballistic regime, scattering regime and alternating barrier injection regime (BARITT) are simulated. The latter allows a negative conductivity even for rather strong scattering.
Ensemble Monte Carlo simulation of electron transport in GaAs/AlAs quantum wire transistor structure is performed. The response of electron drift velocity on the action of harmonic longitudinal electric field is calculated for several values of electric field strength amplitude and gate bias at 77 and 300 K. The periodical electric field has a 1 THz frequency. The nonlinear behaviour of electron drift velocity due to scattering processes is observed.
Ensemble Monte-Carlo simulation of electron and hole transport in deep submicron n-channel SOI MOSFET with 100 nm channel length is performed. The influence of interband impact ionization process on the transistor characteristics is investigated within the framework of Keldysh impact ionization model. Effective threshold energy of electron impact ionization as a parameter characterizing the process is calculated. The dependence of the effective threshold energy on the drain bias is determined.
The Monte Carlo model of electron transport in SOI MOSFETs is proposed. Both 2D and 3D conditions are considered.
The Poisson equation and boundary conditions are presented for every case. Fully depleted SOI MOSFETs and partially
depleted SOI MOSFETs are contradistinguished. The values of electron current as well as drift velocity in different
parts of SOI MOSFETs channel are calculated by means of the Monte Carlo simulation. The SOI MOSFETs with the
channel length equal to 0.5, 0.25 and 0.1 μm as well as the channel depth equal to 10, 20, 100, 200, 1000 nm are
studied. Drift velocity as a function of the channel depth is obtained. It is shown that the function has a peak at the
channel depth equal to 20 nm.
The results of calculation of electron drift velocity in GaAs-in-Al2O3 and GaAs-in-AlAs quantum nanowires as well as
the electric current in the armchair single-wall carbon nanotubes versus time are presented at various electric fields
applied along the structures and different temperature.
In this article the results of calculation of electron scattering rates and the drift velocity of these particles in free standing in vacuum GaAs quantum wire, electron scattering rates via polar optical and acoustic phonons in transistor device structure based on GaAs-in-AlAs quantum wire versus gate voltage, the electric current in armchair single-wall carbon nanotube versus strength of electric field applied along the channel and temperature are presented.
The Monte Carlo model of the impact ionization in deep submicron MOSFETs is worked out. This model allows the influence of the secondary charge carrier current on the drain current to be evaluated. The developed model is built on the basis of the reduction scheme. Moreover, the model takes into account all the major features of electron transport in deep submicron MOSFETs, the dominant scattering mechanisms, the quantization of electron spectrum as well as the modeling of constructive parameters and basic drain breakdown mechanisms.
In present investigation the function of average value of drift velocity versus electric field strength in GaAs quantum wires with various dimensions at temperature T=77 K at electric quantum limit is studied. In the framework of the eveloped model the nonparabolicity is taken into account. The scattering rates in the considered structures are calculated with account both noncollisional and collisional broadening of energy levels.
The ensemble Monte Carlo algorithm for simulation of charge carrier transport in short channel MOSFET was developed. The mobile charge carrier concentration and electrostatic potential calculation procedures were worked out. The drain current increasing mechanisms caused by secondary holes transport in short channel MOSFET were considered. It was found out that at channel length about 0.1 μm the influence of secondary holes transport is quite significant.
The generation of electron drift velocity oscillations in GaAs-quantum wires with finite length at temperature T=77 K in uniform as well as nonuniform field is studied. The influence of wire length and dominant scattering processes on the amplitude, frequency and attenuation of the oscillations is investigated. The average time of electron drift in the various regions of the quantum wire is calculated.