Structural Dependences of Gunn Oscillations in a Planar Nano-Device

2014 ◽  
Vol 618 ◽  
pp. 39-42
Author(s):  
Kun Yuan Xu ◽  
Ya Nan Wang ◽  
Zuo Nian Wang
Keyword(s):  
Monte Carlo ◽  
Threshold Voltage ◽  
Channel Width ◽  
Two Dimensional ◽  
Device Structure ◽  
Ensemble Monte Carlo ◽  
Domain Evolution ◽  
Current Oscillations ◽  
Gunn Effect ◽  
The Asymmetry

Gunn oscillations in a GaAs-based planar nanodevice are studied using a two-dimensional ensemble Monte Carlo (EMC) method. Current oscillations with a frequency of about 0.1 THz have been observed. The current oscillations are accompanied by electron domain evolution along the nanochannel. As such, they can be attributed to Gunn Effect. Further study shows that the Gunn oscillations are not only bias-dependent, but also structural-dependent. The threshold voltage and the amplitude of the oscillations are both related to the channel width and the asymmetry of the device structure.

Steady and Transient Properties of Side-Gated Nano-Transistors

2013 ◽  
Vol 475-476 ◽  
pp. 1363-1367
Author(s):  
Kun Yuan Xu ◽  
Z.N. Wang ◽  
Y. N. Wang
Keyword(s):  
Monte Carlo ◽  
Steady State ◽  
Drain Current ◽  
Transient Processes ◽  
Current Response ◽  
Double Gate ◽  
Two Dimensional ◽  
Ensemble Monte Carlo ◽  
Current Oscillations ◽  
Simulation Results

Using a two-dimensional ensemble Monte Carlo (EMC) method, the steady and transient properties of side-gated nanotransistors with single gate and double gate are studied in detail. Simulation results show that the double-gated nanotransistor has more powerful controlling ability on the channel than the single-gated one. The transient processes of the drain current for the two devices are both about 3 ps, which imply that the working speed of the two devices may reach about 0.3 THz. The detail of transient processes for the double-gated nanotransistor is trivial. But for the single-gated nanotransistor, the drain current response shows obviously oscillating during approaching the next steady state. The phenomenon of drain current oscillations is also discussed.

Noise in a Plasma Wave-Based THz Device

2014 ◽  
Vol 602-605 ◽  
pp. 2732-2735
Author(s):  
K.Y. Xu ◽  
Z.N. Wang ◽  
Y.N. Wang
Keyword(s):  
Monte Carlo ◽  
Plasma Wave ◽  
Plasma Waves ◽  
Noise Spectrum ◽  
Experimental Results ◽  
Two Dimensional ◽  
Drain Voltage ◽  
Ensemble Monte Carlo ◽  
Frequency Maximum ◽  
Simulation Results

Using a two-dimensional ensemble Monte Carlo (EMC) method, the noise spectrum of a InGaAs-based nanoFET is studied in detail. Simulation results show that the noise spectrum consists of two maxima at frequencies of about 0.7 THz and 2 THz. The lower-frequency maximum is sensitive to the source-drain voltage, while that of the higher frequency one is not. These achievements are coincident with experimental results. Moreover, based on Dyakonv-Shur’s theory, the emergence of noise maxima is explained as the excitation of 2D plasma waves in the device.

Structures and crystallization of vacuum-deposited amorphous Se and Sb films

1990 ◽  
Vol 48 (4) ◽  
pp. 140-141
Author(s):  
Makoto Shiojiri ◽  
Toshiyuki Isshiki ◽  
Tetsuya Fudaba ◽  
Yoshihiro Hirota
Keyword(s):  
Monte Carlo ◽  
Electron Microscope ◽  
Monte Carlo Method ◽  
Computer Program ◽  
Radial Distribution ◽  
Film Formation ◽  
Amorphous State ◽  
Two Dimensional ◽  
Amorphous Films ◽  
Binding Condition

In hexagonal Se crystal each atom is covalently bound to two others to form an endless spiral chain, and in Sb crystal each atom to three others to form an extended puckered sheet. Such chains and sheets may be regarded as one- and two- dimensional molecules, respectively. In this paper we investigate the structures in amorphous state of these elements and the crystallization.HRTEM and ED images of vacuum-deposited amorphous Se and Sb films were taken with a JEM-200CX electron microscope (Cs=1.2 mm). The structure models of amorphous films were constructed on a computer by Monte Carlo method. Generated atoms were subsequently deposited on a space of 2 nm×2 nm as they fulfiled the binding condition, to form a film 5 nm thick (Fig. 1a-1c). An improvement on a previous computer program has been made as to realize the actual film formation. Radial distribution fuction (RDF) curves, ED intensities and HRTEM images for the constructed structure models were calculated, and compared with the observed ones.

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