A compact conductive polythiophene (PT) film junction was prepared by potential controlled electrochemical doping after electropolymerization of thiophene. The polythiophene film was cation-doped on one side, while its other side was anion-doped, which resulted in a polythiophene p-n junction film diode. The free-standing polythiophene film junction diode was flexible and was 1.5 times stronger than aluminum metal. After treatment by a strong electric field, the polythiophene p-n junction exhibits a novel electric property like an intelligent electric switch.

Pulsed laser irradiation of oxidized metallic surfaces in an electrolytic cell under proper voltage conditions is demonstrated to be a promising new approach for effective removal of oxide films. Systematic measurements on simulated corrosion-product films by optical reflectance profile and energy dispersive X-ray spectroscopy are used to study the physical mechanisms of this novel phenomenon, the physical conditions for its observation and its possible generality. It was observed that the utilization of a basic electrolyte solution and the imposition of a certain cathodic potential prior to laser irradiation is an essential requirement for a high removal efficiency. This new technique has potential applications in metallurgy, semiconductor fabrication technology and decontamination of nuclear power plans and is suitable for maskless patterning of oxidized surfaces.

Laser ablation of a photosensitive triazene polymer was studied in a micro region by means of a nanosecond imaging technique. The propagation of a blast wave, 100 ns after laser irradiation, sufficiently matched a planar blast wave model including the decomposed source mass which indicates characteristics of a microexplosion. The measured velocities of the fronts indicates two blast waves: an initially fast unsupported wave around the peak of the laser pulse, and a relatively slow supported wave involving the main component of the decomposition.

On laser melt treatment, Sliding Wear of pearlitic ductile iron reduced from severe metallic wear to oxidative mild wear by nearly two orders of magnitude at $7.5 ms^{-1}$ over a load range of $14-31 kg cm^{-2}$; resistance to Cavitation Erosion improved by a factor of seven in corrosive media and surface hardness increased from 20-22 to 40-58 $HR_c$. Laser melting could effectively reduce Corrosion rates in dilute acids by nearly 40%. These improvements were caused by the ultrafine microstructure $(1-4 \mu, DAS)$, microhardness $(700-900, HV_{0,1})$ and the consequent high resistance to plastic flow and subsurface crack initiation. In this investigation, pin-on-disc adhesive wear, ultrasonic vibratory cavitation erosion and potentiodynamic corrosion in synthetic sea water and 0.01 $NH_2SO_4$, were assessed after laser surface melting or transformation hardening of hyper-eutectic ductile iron, typically employed in automotive and marine engine components by using $CO_2$ CW or Nd-YAG pulsed high power laser. Also the processing parameters viz, beam power (P), scan rate (U), and specific energy intensity $(P/UD_b^2)$ for threshold and specific depth of transformation hardening or melting have been determined.

Transparent conducting SnO2 thin films with a thickness between 1000–2000 A were deposited on glass, quartz and silicon substrates using standard pulsed laser deposition techniques with two different targets (Sri and SnO2) and with three different laser wavelengths (1.06, 0.532 and 0.266 μ) from a Q-switched Nd: YAG laser. Tin dioxide films with optical transmission over most of the visible spectrum exceeding 80% were obtained using a Sn target and a background oxygen pressure of 20 Pa. The electrical resistivity (ρ) depended strongly on the substrate temperature during deposition, with the lowest values ofρ of about 10−2 Ω-cm obtained when the substrate was maintained at 400°C during deposition. Using SnO2 targets, predominantly amorphous phase SnO2 films were deposited on Si substrates and then transformed into polycrystalline Sn3O4 by laser induced crystallization (λ = 1.06 μm). Whereas these later films were essentially non-conducting as deposited (ρ > 400 Ω-cm), the electrical resistivity was permanently reduced after laser induced crystallization by a factor greater than 1000 to a value of approximately 4 × 10−1 Ω-cm.

The modified electrostatic model (Neumann and Tolle 1995) is applied to the impurity diffusion in nickel. Z o = 0.4 is used for the effective charge of the nickel ion. The comparison of calculated and experimental diffusion parameters reveals that the sign of ΔQ, the difference between impurity diffusion and self-diffusion energy, and the sign of the difference between impurity diffusion and self-diffusion coefficient is correctly predicted in all cases. On the other hand the comparison exhibits some systematic deviations for 5p impurities, which cannot be explained in terms of the current impurity diffusion models.

Optical absorption coefficient spectra of thin silicon films were precisely investigated using a simple reflectance system with total reflectance mirrors placed on the rear side of samples in order to cancel an interference effect in a range between 1.1 eV and 3 eV. The absorption coefficient decreased according to crystallization as the laser energy increased and it got similar to that of single crystalline silicon in the range of 1.7 eV ∼ 3 eV. However, the absorption coefficient was higher than 102 cm−1 in the photon energy lower than 1.3 eV. This probably results from band tail states caused by defect states localized at grain boundaries in the crystallized films. 2.5%-phosphorus doped laser crystallized silicon films had a high optical absorption coefficient ( > 104 cm−1) in the low photon energy range (1.1 eV ∼ 1.7 eV) caused by free carriers produced from the dopant atoms activated in the silicon films. The experimental results gave the carrier density of 1.3 × 1021 cm3 and the carrier mobility of 20 cm2/Vs.

Laser-induced desorption of metal atoms at low rate has been studied for pulsed excitation with wavelengths of λ = 266, 355, 532 and 1064 nm. For this purpose sodium adsorbed on quartz served as a model system. The detached Na atoms were photo-ionized with the light of a second laser operating at λ = 193 nm and their kinetic energy distribution was determined by time-of-flight measurements. For λ = 1064 nm a distribution typical of thermal bond breaking is observed. If desorption, however, is stimulated with light of λ = 266 or 532 nm, the kinetic energy distribution is non-thermal with a single maximum atEkin = 0.16 ± 0.02 eV. For λ = 355 nm the non-thermal distribution is even bimodal with maxima appearing atEkin = 0.16 ± 0.02 and 0.33 ± 0.02 eV. These values of the kinetic energies actually remain constant under variation of all experimental parameters. They appear to reflect the electronic and geometric properties of different binding sites from which the atoms are detached and thus constitute fingerprints of the metal surface. The non-thermal desorption mechanism is discussed in the framework of the Menzel-Gomer-Redhead scenario. The transition from non-thermal to thermal desorption at large fluentes of the laser light could also be identified.

Surface topology changes in polyimide induced by single UV-laser pulses with pulse durations between 140 ns and 5 μs are investigated by means of atomic force microscopy. With increasing fluence three different regimes are found: (a) real material removal (ablation), (b) swelling of the irradiated area above the level of the untreated surface (hump formation) and (c) lowering of the irradiated area below the level of the untreated surface (dent formation). A detailed description of these topology changes is given and different formation processes are discussed.