Drift velocity

About: Drift velocity is a research topic. Over the lifetime, 6897 publications have been published within this topic receiving 129602 citations. The topic is also known as: drift speed.

Study On Effect Of Photo-illumination On Si/SiC Asymetrical Superlatice Avalanche Transit Time Device: A High Power Terahertz Room Temperature Source

Abstract: The paper deals with comparative study and analysis of Si/4H-SiC asymmetrically doped superlattice based Avalanche Transit time (ATT) device, operating at Terahertz frequency region, under normal and photo-illuminated conditions. A generalised non-linear quantum drift diffusion model is developed for the analysis. The simulation study reveals that due to the superlattice structure, the device is capable of generating a considerable amount of power density (~2.7x1011 Wm-2) at 0.5 THz with an efficiency of ~ 46%, at 50% voltage modulation under normal (unilluminated) condition. Whereas, under photo-illumination, keeping the amount of percentage modulation fixed, significant change in output power density and efficiency, due to the effect of additional photo-generated charge-carriers, are found. The authors have made the analysis realistic by incorporating the temperature dependent carrier ionization rate, saturation drift velocity, mobility and effective mass along with enhanced leakage current effect due to photon absorption. To the best of authors’ knowledge, this is the first report on non-linear optical analysis of Si/4H-SiC superlattice ATT device at higher Terahertz region.

Comparative study of mathematically modelled High Electron Mobility Transistors and silicon nanowire transistors

Abstract: This work concentrates on the mathematical modeling of High Electron Mobility Transistors (HEMTs). Fermi-Dirac distribution characteristics of HEMTs and Silicon Nano-wire Transistors (SNWTs) were compared. Our mathematical modelling involves study of V-I characteristics, Electric field versus Drift velocity characteristics, ID electron density versus position characteristics, transconductance versus gate-source voltage characteristics, unity gain cut off frequency versus gate-length characteristics, mobility versus temperature characteristics and Density of states versus position characteristics. According to this model, Transferred Electron Devices (TEDs) has better drift velocity versus electric field characteristics compared to GaAs Metal Semiconductor Field Effect Transistors (MESFETs), and SNWTs have better V-I characteristics compared to HEMT. GaAs/AlGaAs HEMTs have better transconductance and unity gain cut-off frequency than GaAs HEMTs. HEMTs modelled using ballistic mobility method have better V-I characteristics compared to SNWTs. GaN HEMTs have high mobility compared to GaAs HEMTs. SNWTs have better density of states characteristics compared to GaN HEMTs.

A determination of the charge state of energetic magnetospheric ions by the observation of drift echoes

Abstract: The mean charge states of heavy ions trapped in the earth's magnetosphere are important parameters for distinguishing among magnetospheric theories. No direct measurements have been made at energies greater than ∼ 50 keV. A technique, which uses the E/q dependence of ion drift velocity, is described in this letter. A drift-echo event, which followed a substorm that occurred at 2100-2200 UT on 25 February 1979, is discussed to illustrate the application of this technique. In this event the charge state of helium ions was +2 and CNO ions was > +2 and probably ≥ +5. This result implies that the drift-echo particles were from freshly injected solar-wind plasma.