The temperature-dependent physical and electrical characteristics of a polymer/RAFT-polymer stabilized nanoparticle system for organic nonvolatile memory.

We have fabricated and investigated organic memory diodes, comprising a single polymer layer and Au nanoparticles stabilized by the same polymer material utilizing a reversible addition-fragmentation transfer technique to suppress phase separation. The organic memory diodes exhibit well reproducible and prominent current bistability and good charge retention characteristics free from phase separation issues. Nondestructive spectroscopic ellipsometry is used to characterize the physical properties of the polymer/nanoparticle composites, such as the polymer's effective dielectric function/layer thickness and the Au nanoparticle's effective volume fraction, which are important parameters for gaining insightful information on charge transport in this system. Temperature-dependent analysis of the read/write current behaviors suggests that charge transport in such a polymer/Au nanoparticle composite is dominated by carrier hopping via shallow-level traps at the high field regime.

Symmetry selected quantum dynamics of few electrons in nanopillar transistors.

Study on single electron tunnel using current-voltage characteristics in nanopillar transistors at 298 K show that the mapping between the Nth electron excited in the central box ∼8.5 × 8.5 × 3 nm3 and the Nth tunnel peak is not in the one-to-one correspondence to suggest that the total number N of electrons is not the best quantum number for characterizing the quality of single electron tunnel in a three-dimensional quantum box transistor. Instead, we find that the best number is the sub-quantum number nz of the conduction z channel. When the number of electrons in nz is charged to be even and the number of electrons excited in the nx and ny are also even at two, the adding of the third electron into the easy nx/ny channels creates a weak symmetry breaking in the parity conserved x-y plane to assist the indirect tunnel of electrons. A comprehensive model that incorporates the interactions of electron-electron, spin-spin, electron-phonon, and electron-hole is proposed to explain how the excited even electrons can be stabilized in the electric-field driving channel. Quantum selection rules with hierarchy for the ni (i = x, y, z) and N = Σni are tabulated to prove the superiority of nz over N.