Silicide formation in implanted channels and interfacial reactions of Ni, Co, Ti, and Cu contacts under high current density have been investigated. Silicide lines, forming in the implanted channels, were observed in Ni and Cu/p+–Si samples but not in Ti and Co samples. The silicide line formation is correlated to the high diffusivity of metals in Si. For the Ni/p+–Si sambles, silicode line was found to initiate form the cathode contact. Network structures at the cathode were found in both Co and Ni samples. The depth of silicide formation was found to extend to the junction depth. The relationships between the silicide length and contact size, the applied current, and the method of the applied current are discussed.

The effects of a seeding layer, which was deposited on Pt/TiO2/SiO2/Si substrates using magnetron sputtering, on the characteristics of sol-gel-deposited strontium-bismuth-tantalate (SBT) thin films are investigated. The seeding layer serves as nucleation sites so homogeneous crystalline SBT films of bismuth-layered structure (BLS) with fine grains are successfully obtained by 750°C rapid thermal annealing in O2 ambient. The remanent polarization (2Pr) improves from 12.1 to 18.8 µC/cm2 with the addition of the seeding layer. In addition, the seeding layer also results in a lower nucleation temperature, allowing the use of 700°C annealing for 10 min to grow SBT films that are fully crystallized with BLS phase and shows good ferroelectric properties. Finally, crystallinity and microstructures of SBT films are found to be strongly dependent on the thickness of the seeding layer. Optimum Ta-seeded SBT thin film crystallized at 700°C for 10min depicts a higher 2Pr value (12.9 µC/cm2 (@5V) than that of the un-seeded films crystallized at 750°C for 1min.

High-resolution transmission electron microscopy in conjunction with autocorrelation function analysis have been applied to investigate the evolution of structural order in Ge+-preamorphized silicon layers. (001)Si wafers were preamorphized with 5 and 10keV Ge+ to a dose of 5×1015ions/cm2. A higher density of embedded nanocrystallites was found to be present in as-implanted amorphous Si layer for 10keV Ge+ than that for 5keV Ge+. The densities of embedded nanocrystallites in Ge+-preamorphized Si layer with 5 and 10keV Ge+ were found to diminish with annealing temperature first then increase. The effects of ion-implantation energy and annealing temperature on the structural evolution in Ge+-implanted amorphous Si are discussed in terms of ion-beam induced annealing and free energy change of the system. The depth dependence on the density of embedded nanocrystallites is attributed to the nonuniform distribution of Ge atoms.

Films of well-ordered crystalline copper oxide (CuO) nanofibril arrays were synthesized using a procedure involving electrodeposition followed by a gas-solid reaction. Analyses showed that the nanocrystalline CuO nanofibrils with a mean length of 8 μm have an average density of 107–108/cm2. Photoluminescence measurements showed a main peak in the visible light band at 410 nm, and the band gap energy was estimated to be 1.67 eV. It was found that the film of aligned CuO nanofibrils has typical Fowler–Nordheim plots in the follow-up electron field emission test. Typical turn-on voltage was detected at ∼6 V/μm with an emission area of 1 mm2. The Fowler–Nordheim model was employed to analyze the I–V data obtained. The work function of the nanofibrils was estimated to be in the range of 4.1–4.3 eV.

One-dimensional and well-ordered CuO nanofiber arrays have been synthesized by a processing of self-catalytic growth. Using polycarbonate (PC) membrane as a template, copper nuclei sites Cu(111) were uniformly deposited on copper substrate via a high voltage input (electric field: 15 V/cm) in a copper sulphate solution. According to the pore diameter of PC membranes, two different sizes of copper nuclei could be well-controlled in ranges of 50 to 60 and 100 to 150 nm. With heat treatment in oxygen atmosphere, the electrodeposited copper nuclei were transformed into CuO nanofiber arrays. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses showed that the nanocrystalline CuO nanofibers with a mean length of 8 μm had an average order of 107–108/cm2 in density, and their average diameters were accorded with the size of Cu nuclei.

Ultrafast directional crystallization that combined the electric current stressing with metal-induced crystallization has been achieved for BF2+-implanted amorphous Si (a-Si) at room temperature. Polycrystalline Si was observed to grow from anode towards cathode and the channels of a-Si strips with a length of 140 mum and a width of 10 mum can be fully crystallized with a stressing time less than 0.2 s. The directional growth of crystalline Si nanowires, 50 nm in width and as long as 3 mum in length, with an extraordinarily high aspect ratio of 60, indicates a strong electric-field-induced effect on the growth. The growth method provides a promising scheme to solve the problems caused by high-temperature and long-term annealing treatment for the applications of optoelectronic devices. (C) 2003 American Institute of Physics.

Three types of CuO nanostructures—the nanorod, nanofiber, and nanoparticle—have been grown by using a self-catalytic growth process at 400, 500, and 600 °C, respectively. Field-emission (FE) properties of the CuO nanostructures were investigated. The results indicated that the FE current was significantly affected by the morphologies of the CuO samples. Typical turn-on voltage for the CuO nanofiber array was detected at about 6–7 V/μm with an emission area of 1 mm2. Based on Fowler–Nordheim plot, the values of work function for the nanofiber array were estimated in ranges of 0.56 to 2.62 and 0.30 to 1.39 eV from a two-stage linearity plot. X-ray photoelectron spectroscopy analysis showed no obvious changes in chemical composition of the nanofiber array before and after FE tests. According to the analyses, the highly ordered CuO nanofiber array can be a promising candidate for FE emitters.

The structural evolution in Ge+ implantation amorphous Si has been investigated by high-resolution transmission electron microscopy in conjunction with auto-correlation function (ACF) analysis. Si(001) wafers were implanted with 5keV Ge+ to a dose of 5×1015 ions/cm2. A high density of embedded nanocrystallites was found to be present in as-implanted amorphous Si. After 350°C annealing, the density of nanocrystallites was found to decrease, but increase after annealing at 400°C or higher temperatures. The observation indicated that the implanted silicon became more randomized upon annealing up to 350°C. The results are discussed in terms of energy variation in the system.

The existence of medium-range ordering structures or nanocrystallites in as-deposited amorphous SiGe thin films has been demonstrated by high-resolution transmission electron microscopy in conjunction with auto-correlation function analysis. The density of nanocrystallites decreases in amorphous SiGe samples annealed at 300–350°C then increases in samples annealed at 400–450°C with annealing temperature. The observations can be interpreted in terms of free energy change with annealing temperature.

High-resolution transmission electron microscopy (HRTEM) in conjunction with auto-correlation function (ACF) analysis has been applied to investigate the crystallization processes in amorphous silicon. For both electron beam evaporated and ion implanted amorphous silicon thin films, a high density of Si nanocrystallites was detected in as-deposited films. The density was found to diminish in amorphous films with annealing temperature first then increase. The conclusions are discussed in the context of free energy change with annealing temperature.

High-resolution transmission electron microscopy in conjunction with autocorrelation function analysis have been applied to investigate the evolution of structural order in germanium ion-implanted amorphous silicon (a-Si) layers. A high density of Si nanocrystallites as small as 1 nm in size was detected in as-implanted a-Si layers. The density of embedded nanocrystalline Si was found to diminish in a-Si layers with annealing temperature first then increase. The results are discussed in the context of free energy change with annealing temperature.

The structural evolution in amorphous silicon and germanium thin films has been investigated by high-resolution transmission electron microscopy (HRTEM) in conjunction with autocorrelation function (ACF) analysis. The results established that the structure of as-deposited semiconductor films is of a high density of nanocrystallites embedded in the amorphous matrix. In addition, from ACF analysis, the structure of a-Ge is more ordered than that of a-Si. The density of embedded nanocrystallites in amorphous films was found to diminish with annealing temperature first, then to increase. The conclusions also corroborate well with the results of diminished medium-range order in annealed amorphous films determined previously by a variable coherence microscopy method.

Enhanced dopant activation and elimination of end-of-range (EOR) defects in BF2+-implanted silicon-on-insulator (SOI) have been achieved by high-density current stressing. With the high-density current stressing, the implantation amorphous silicon underwent recrystallization, enhanced dopant activation and elimination of the (EOR) defects. The current stressing method allows the complete removal of EOR defects that has not been possible with conventional thermal annealing in the processing of high-performance SOI devices.

Ultrafast diffusion of Cu and Ti atoms in p+-Si channel was achieved in samples stressed with high current density. The junction was changed under high current stress and copper silicide was formed in the junction. The current effects of high current on the silicide line formation and symmetrical end-of-range defects elimination near the center of p+-Si channel are discussed.

Ultrafast diffusion of Ni and Cu atoms in p(+)-Si channel was observed. Contact failed at negative contact first, possibly by electron-hole recombination at the negative electrode. Ti diffusion assisted by Cu under high current density was observed in the Cu and Ti multilayered samples. Ti atoms at Ti contact cannot migrate into the diffusion channel but can be carried by Cu atoms. In addition, Cu and Ti easily interdiffused under high current density. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

Experimental techniques for growing CuInS2 layers on GaP substrates by the metalorganic method have been developed. Hydrogen sulfide gas together with the vapors of CuCl(NCCH3)n and InCl3(NCCH3) both of which were generated by bubbling nitrogen through sources, using a solvent of acetonitride, were used as transport agents. Various characterization techniques such as atomic absorption (AA), neutron activation analysis (NAA), energy dispersive analysis by X-rays (EDAX), Rutherford back-scattering analysis (RBS), and X-ray analyses were used to help understand the fundamental mechanism of the CVD growth.