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Intensive electroluminescence (EL) visible to the naked eyes is observed from p–i–n structure light emitting diodes with nanocrystalline Si (nc-Si) film as the luminescent layer. It is found the luminescence intensity increases by 20 times compared with that of nc-Si film without p-i-n structure and the turn-on voltage is sharply reduced. Combined with I-V and TEM analysis, the improved EL is attributed to the enhancement of carrier injection probability of nc-Si inserted in p-i-n structure.

Vertically aligned carbon nanotubes (CNTs) with controllable length and diameter fabricated by microwave plasma enhanced chemical vapor deposition (MPECVD) are of continuing interest for various applications. This paper describes the role of process gas composition as well as the pre‐coating catalytic layer characteristics. It is observed that nucleation of CNTs was significantly enhanced by adding nitrogen in the MPECVD process, which also promoted formation of bamboo‐like structures. The very first key step toward growth of aligned CNTs was the formation of high‐density fine carbon onion encapsulated metal (COEM) particles under a hydrogen plasma. Direct microscopic investigation of their structural evolution during the very early stages revealed that elongation, necking, and splitting of the COEM particles occurred accompanying the growth of CNTs, such that one of the split portions rode on the top of the growing tube while the remaining one resided on the root. Our results suggest that CNTs grow via the “tip‐growth” as well as “root‐growth” mechanisms.

CdS-mercaptoacetic (CdS/M) clusters were synthesized by using mercaptoacetic acid as the stabilizing agent in the aqueous solution. From the transmission electron microscopy (TEM) image and the electron diffraction (ED) pattern, a two-dimensional nearly ordered CdS/M cluster array is observed and the CdS/M cluster is found to be constructed of small CdS/M nanocrystals. The model of self-assembly of the CdS/M clusters with internal structure is presented. The absorption spectrum of the CdS/M nanocrystal solution reveals a maximum at 372 nm and the corresponding photoluminescence (PL) spectrum shows a strong peak at 556 nm at room temperature. The PL spectra of various concentrations of CdS/M reveal the passivation effect of mercaptoacetic acid.

The synthesis of several 4-pyridylacetyl N-oxide derivatives of 4-(3-bromo-6,11-dihydro-5H-benzo[5,6]-cyclohepta[1,2-b]pyridin-11-yl)piperazine/piperidine 3Figure 2is described. This study was aimed at identifying fomesyl protein transferase (FPT) inhibitors in these two series of tricycles containing different phenyl ring substituents. The in vitro activity profile of the initial group of compounds 7a–7gScheme 1Reagents: (a) i. LDA/THF/−78°C/R-PhCH2Br; ii. POCl3/PhCH3/80°C. (b) i. CF3SO3H/rt, or AlCl3/CH2Cl2, or AlCl2/150°C; ii. 4N HCL/110°C. (c) i. LDA/THF/−78°C/2-Cl-5-MeO-PhCH2Br; ii. POCl3/PhCH3/80°C; iii. CF3SO3H/rt; iv. 4N HCl/110°C. (d) i. Bu4N+NO3−/(CF3CO)2O/CH2Cl2/rt; ii. HCO2NH4/MeOH/10%Pd-C/reflux; iii. CuBr2/tertBuONO/CH3CN/0°C. (e) i. NaBH4/EtOH; ii. SOCl2/CH2Cl2; iii. Piperazine/CH2Cl2; iv. EDCI/HOBT/NMM/4-pyridylacetic acid N-oxide/DMF. (f) HPLC/ChiralPak AD column.led to the synthesis of the 8-methyl-10-methoxy and 8-methyl-10-bromo analogues 7i, 13i, and 13jScheme 3Reagents: (a) N-Me-4-piperidinyl-MgCl/THF. (b) i. PPA/160°C; ii. ClCo2Et/PhCh385°C; iii. 4N HCl/130°C. (c) i. N-Me-4-piperiddinyl-MgCl/THF; ii. CF3SO3H/4°C; iii. ClCO2Et/PhCH385°C; iv. 4N HCl/130°C. (d) i. ClCO2Et/PhCh370°C; ii. 4N HCl/110°C. (e) EDCI/HOBT/NMM/4-pyridylacetic acid N-oxide/DMF. (f) DIBAL H/PhCH3/rt. (g) HPLC/ChiralPak AD column.. The 11R(−) enantiomers of these compounds were found to exhibit potent in vitro FPT inhibition activity.

Compton profiles of polycrystalline lithium were measured at 90 and 300K, using synchrotron radiation. We detected a slight change with temperature, but its magnitude was found to be much smaller than predicted by recent calculations and its dependence on momentum was much different from the recent prediction.

We have observed visible photoluminescence (PL) at room temperature in crystallized a-Si:H/a-SiNx:H multiquantum-well (MQW) structures with LS≤4 nm. A detailed PL study, which deals with the temperature and excitation density dependence of PL peak intensity, indicates that the electron-hole confinement effect plays a predominant role in visible PL in crystallized MQW structures with thin well layers at higher temperature.

Crystallized aGe:H/aSiNX:H multiquantum-well (MQW) structures were prepared by a computer controlled plasma enhanced chemical vapor deposition method and then crystallized by Ar+laser annealing technique. The layered structures and the crystallinity of the samples were determined by means of X-ray diffraction (XRD) spectroscopy. The crystallized samples showed a radiative transition with visible light as the Ge well layer thickness was less than 4 nm. This may preliminary be explained by the quantum confinement of electrons and holes.

Surface Rayleigh acoustic waves and related elastic properties of quasiperiodic and periodic modulated a-Si:H/a-SiNx:H superlattices have been studied by means of a light-scattering technique. Changes in the phase velocity of the surface Rayleigh acoustic waves as a function of sublayer (a-Si:H) thickness are interpreted using an effective medium model. Despite the existence of structural mismatch in the bond-length and coordination number and of structural disorder in the bond-angle for Si-N and Si-Si, no appreciable discrepancy between the measured results and the theoretical predictions has been found.

A new approach to reducing the source resistance in InP-based InAlAs/InGaAs enhancement-mode HEMTs is developed using Pt-based buried-gate technology. Source resistance as small as 0.2 Ωmm is obtained, which results in an excellent transconductance of 1170 mS/mm for a 0.5 µm long gate enhancement-mode HEMT.

A novel approach to modulating resonant-tunnelling current is demonstrated based on the monolithic integration of RTDs and FETs. As an example for circuit application, the first reset-set flipflop circuit using resonant-tunnelling devices is demonstrated.