Electroluminescence emission of crystalline germanium nanoclusters deposited with laser assistance at low temperature.

With CO2 laser assistance, crystalline Ge nanocluster-embedded Ge films were deposited at low temperature using a conventional plasma-enhanced chemical vapor deposition system. Raman spectrum showed a wavenumber peak at 290 cm(-1) which corresponded to the crystalline Ge nanoclusters in the Ge film deposited with CO2 laser assistance. Crystalline Ge nanoclusters embedded in Ge matrices were observed from transmission electron microscopy (TEM) images and electron diffraction pattern. The electroluminescent devices constructed with multilayered Ge nanoclusters-embedded Ge films were fabricated. The experimental results demonstrated that the electroluminescence emission originated from the radiative recombination of the electron-hole pairs in the Ge nanoclusters.

Memory characteristics of metal-oxide-semiconductor structures based on Ge nanoclusters-embedded GeO(x) films grown at low temperature.

The memory devices constructed from the Ge-nanoclusters embedded GeO(x) layer deposited by the laser-assisted chemical vapor deposition (LACVD) system were fabricated. The Ge nanoclusters were observed by a high-resolution transmission electron microscopy. Using the capacitance versus voltage (C-V) and the conductance versus voltage (G-V) characteristics measured under various frequencies, the memory effect observed in the C-V curves was dominantly attributed to the charge storage in the Ge nanoclusters. Furthermore, the defects existed in the deposited film and the interface states were insignificant to the memory performances. Capacitance versus time (C-t) measurement was also executed to evaluate the charge retention characteristics. The charge storage and retention behaviors of the devices demonstrated that the Ge nanoclusters grown by the LACVD system at low temperature are promising for memory device applications.

Charge storage characteristics of silicon nanoclusters in silicon nitride matrix grown by laser assisted chemical vapor deposition method.

The capacitance-voltage (C-V) and charge retention characteristics of the metal-insulator-semiconductor (MIS) structure, in which the insulator layer was composed of silicon nanocluster-embedded silicon nitride, were studied. The memory effect of this MIS structure was dominantly attributed to the charge storage in the silicon nanoclusters. The relation between the flatband voltage shift and the amount of charges stored in the nanocluster-embedded insulator layer was discussed. The capacitance-time (C-t) relation of MIS structures, conventionally used to follow the discharge process, was further analyzed, indicating that care should be taken in the C-t measurement for obtaining correct discharging behavior. Then the charge retention characteristics of the fabricated MIS structures under various charging conditions were derived by the capacitance-time (C-t) measurement. The results showed that the devices, charged for a longer time or under a lower charging voltage, discharge slower. The observed charge retention behaviors can be reasonably attributed to the spatial distribution of silicon nanoclusters in the silicon nitride layer and the dispersion of the nanocluster sizes