Monday, June 28, 2010

some reading for summertime

Appl. Phys. Lett. 96, 253301 (2010); doi:10.1063/1.3453661 (3 pages)

Current bistability and carrier transport mechanisms of organic bistable devices based on hybrid Ag nanoparticle-polymethyl methacrylate polymer nanocomposites

Won Tae Kim, Jae Hun Jung, Tae Whan Kim, and Dong Ick Son
Abstract:The current bistability and the carrier transport mechanisms of organic bistable devices (OBDs) using Ag nanoparticle-polymethyl methacrylate (PMMA) nanocomposites have been investigated. Current-voltage measurements at 300 K on the Al/Ag nanoparticles embedded in the PMMA layer/indium-tin-oxide devices exhibit a current bistability with an ON/OFF ratio of 103. Write-read-erase-read sequence results demonstrate the switching characteristics of the OBD. The cycling endurance number of the ON/OFF switching for the OBD is above 7×104. The current bistability and carrier transport mechanisms of the OBD fabricated utilizing hybrid Ag nanoparticle-PMMA polymer nanocomposites are described on the basis of the experimental data.

Quantum transport modeling of defected graphene nanoribbons 
 I. Deretzis, G. Fiori, G. Iannaccone, G. Piccitto and A. La Magna

Abstract: We study backscattering phenomena during conduction for graphene nanoribbons of μm lengths, from single vacancy scatterers up to finite defect concentrations. Using ab initio calibrated Hamiltonian models we highlight the importance of confinement and geometry on the shaping of the local density of states around the defects that can lead to important alterations on the transport process, giving rise to impuritylike conduction gaps in the conductance distribution. Within a statistical analysis of finite defect concentration we show that conductance degradation can become very important.

 Solid-State Electronics
The spatial origin of current noise in semiconductor devices in the framework of semiclassical transport
C.E. Kormana, B.A. Noaman

Abstract: A new model to semiconductor device electronic noise is presented in the framework of semiclassical transport theory. The salient feature of this model is that it connects the current noise characteristics directly to the physics of scattering of the semiclassical transport theory and makes no additional assumption regarding the nature of noise. Employing this approach, this work investigates the spatial origin of the current noise across two semiconductor structures. In this approach the terminal current noise is directly related to carrier scattering inside the device, which is accounted for in the Boltzmann transport equation (BTE), without the need to add Langevin noise terms to the calculations. Accordingly, it utilizes the well-established spherical harmonics expansion (SHE) technique to solve the BTE, and it combines analytical and numerical methods, in contrast with the Monte Carlo (MC) approach that employs ensemble averages of randomly generated events. The model leads to the solution of a time-dependent transient solution of the BTE with special initial and Ohmic boundary conditions that is solved in the frequency domain to directly compute the terminal current noise spectral density. It is also shown that with this approach the Nyquist theorem under thermal equilibrium conditions is recovered.


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