Papers by Keyword: Nanodevice

Abstract: 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.

Abstract: Atomic layer deposition (ALD) has been a key player in advancing the science and technology of nanomaterials synthesis and device fabrication. The monolayer (ML) control of growth rate obtained with ALD combined with its ability to self-limit growth reactions at the gas-substrate interface can be exploited in fundamentally new ways to produce novel composite nanomaterials or precisely tailored 3D nanostructures. Fueling the rapid popularity of ALD in nanotechnology research is the relative simplicity of the hardware and exciting new chemistries that allow researchers to deposit a host of new materials including pure metals, metal oxides, sulphides and nitrides and organic thin films with relative ease and superb accuracy. In this review article, we present four impact areas - microelectronics, energy harvesting and energy storage devices and sensors and photonic devices that have benefitted from such an approach. While many excellent review articles are available on the fundamental chemistry of ALD processes, we focus here on the applied science and engineering aspects of cutting edge ALD research

Abstract: InP nanocrystals were prepared by an economic chemical reaction. A very high density of surface states is found at 0.5 eV below the intrinsic conductive band edge. Mixing these InP nanocrystals with MEH-PPV, obtained the composite. Devices with structure ITO/composite(MEH-PPV)/Al were fabricated and investigated. Photocurrent spectra showed that the interface between a conjugated polymer and a semiconductor nanocrystal can be used to provide efficient charge separation for neutral excitons on both the ground states and excited ones. Incorporation of nanocrystals, the conductivity of diode shows large improvements.

Abstract: Efficient assembly of nanowires or nanotubes into functional nanodevices is one of the keys for practical application of the promising nanotechnology. Generally there are two ways for the assembly of nanowires or nanotubes: directed assembly during growth and post-growth assembly. The post-growth assembly technique is advantageous in some aspects comparatively for it puts little limitation on the nanowire or nanotube materials involved, and it can produce large nanowire arrays with better consistency. So this paper reviewed post-growth nanowire assembly techniques and discussed their advantages and shortcomings.

Abstract: The nanostructures and nanodevices special fabrication technology including electron beam lithography (EBL), focused ion beam (FIB) technology, microcontact printing (μCP) and nanoimprinting were introduced in this paper. The examples of Y-shape waveguide coupler and high precision nanopattern of China Seal were designed and fabricated based the EBL and FIB technology respectively. Their structures can be characterized by scanning electron microscopy (SEM), scanning tunnel microscopy (STM) and atom force microscopy (AFM) etc. The C60 molecular on a Si (111)-(7×7) surface in variable temperature is deposited and detected by STM. The fabricated pattern and structures results indicated that the novel fabrication and characterization technology is very important and effective tools in nanoscale science field.

Abstract: The singular nature of the Boltzmann transport equation leads to the boundary layer structure around the virtual source in nano-scale device structures. We show that the boundary layer is a key concept to understand the physical mechanism behind quasi-ballistic transport in nano-scale devices. The self-consistent 3D Monte Carlo device simulator is constructed by accurately including the full Coulomb interaction. It is explicitly shown that the Coulomb interaction is indeed a key ingredient for any reliable predictions of device characteristics.

Abstract: Quantum correction model features the correction of the inversion layer charge on different classical transport models in semiconductor device simulation. This approach has successfully been of great interest in the recent years. Considering a metal-oxide-semiconductor (MOS) structure in this paper, the Hänsch, the modified local density approximation (MLDA), the density-gradient (DG), the effective potential (EP), and our models are investigated computationally and compared systematically with the result of the Schrödinger-Poisson (SP) model. In terms of the accuracy for (1) the position of the charge concentration peak, (2) the maximum of the charge concentration, (3)the total inversion charge sheet density, and (4) the average inversion charge depth, these well-established models are examined simultaneously. The DG model requires the solution of a boundary value problem, the EP model overestimates the position of the charge concentration peak and the maximum of the charge concentration, our explicit model demonstrates good accuracy among models.