Enhanced charge storage characteristics of silicon nanocrystals fabricated by electron-beam coevaporation of Si and SiOx(x=1 or 2)

In this article, a simple and flexible electron-beam coevaporation (EBCE) technique has been reported of fabrication of the silicon nanocrystals (Si NCs) and their application to the nonvolatile memory. For EBCE, the Si and SiOx(x=1 or 2) were used as source materials. Transmission electron microscopy images and Raman spectra measurement verified the formation of the Si NCs. The average size and area density of the Si NCs can be adjusted by increasing the Si:O weight ratio in source material, which has a great impact on the crystalline volume fraction of the deposited film and on the charge storage characteristics of the Si NCs. A memory window as large as 6.6 V under +/- 8 V sweep voltage was observed for the metal-oxide-semiconductor capacitor structure with the embedded Si NCs.

Photovoltaic effect in a photon storage cell

The response of photonic memory effect in I-V characteristics of a specially designed photonic memory cell was reported. When the cell is biased in a storage mode, the optical excitation with the photon's energy larger than the energy gap gives rise to a step-like jump in the current. A set-up was used to measure the transient photocurrent at the biases where the step-like jump showed up. It is proved that the falling transient edge of the photocurrent, as the photoexcitation turns off, mainly maps the decaying of electrons and holes, which were previously stored in the cell during the illumination. Its time constant is a measure of photonic memory time.