The spatial and temporal evolution of the absolute electron densities and temperatures in plasmas formed by nanosecond pulsed laser ablation of silicon in vacuum at two wavelengths (1064 and 532 nm), at similar irradiances, have been explored by complementary simulation (using combined hydrodynamic and adiabatic models) and experiment. Modelling the laser-target and laser-plume interactions with the POLLUX code reveals the evolving composition and dynamics of the laser induced plasma (LIP) during the incident laser pulse: 532 nm irradiation causes more ablation, but the LIP formed by 1064 nm excitation has a higher average charge state and expands faster. The experimental data, from the analysis of Stark broadened line shapes of SiIII and SiIV cations in time-gated, position- and wavelength-resolved images of the plume emission, allow characterisation of the plume dynamics at later times. These dynamics are compared with predictions from two forms of adiabatic expansion model. Both take as input parameters the plume properties returned by the POLLUX simulations for the end of the laser pulse, but differ according to whether the initial plasma is assumed isothermal or isentropic. The study illustrates the important λ-dependences of the target absorption coefficient (in establishing the ablated material density) and of electron–ion inverse bremsstrahlung absorption (in coupling laser radiation into the emergent plasma); the extents to which these interactions, the relative ablation yields, and the plume expansion dynamics depend on λ; and the importance of identifying appropriate initial conditions for adiabatic expansion modelling of LIP in vacuum.

Plasma-Enhanced Pulsed Laser Deposition (PE-PLD) is a technique for depositing metal oxide thin films that combines traditional PLD of metals with a low-temperature oxygen background plasma. This proof-of-concept study shows that PE-PLD can deposit copper oxide and zinc oxide films of similar properties to ones deposited using traditional PLD, without the need for substrate heating. Varying the pressure of the background plasma changed the stoichiometry and structure of the films. Stoichiometric copper oxide and zinc oxide films were deposited at pressures of 13 Pa and 7.5 Pa, respectively. The deposition rate was ∼5 nm/min and the films were polycrystalline with a crystal size in the range of 3 nm–15 nm. The dominant phase for ZnO was (110) and for CuO, they were (020) and (111¯), where (020) is known as a high-density phase not commonly seen in PLD films. The resistivity of the CuO film was 0.76 ± 0.05 Ω cm, in line with films produced using traditional PLD. Since PE-PLD does not use substrate heating or post-annealing, and the temperature of the oxygen background plasma is low, the deposition of films on heat-sensitive materials such as plastics is possible. Stoichiometric amorphous zinc oxide and copper oxide films were deposited on polyethylene (PE) and polytetrafluoroethylene (PFTE).

In this study, plasma-enhanced pulsed laser deposition (PE-PLD), which is a novel variant of pulsed laser deposition that combines laser ablation of metal targets with an electrically-produced oxygen plasma background, has been used for the fabrication of ZnO and Cu 2 O thin films. Samples prepared using the PE-PLD process, with the aim of generating desirable properties for a range of electrical and optical applications, have been analysed using medium energy ion scattering. Using a 100 keV He + ion beam, high resolution depth profiling of the films was performed with an analysis of the stoichiometry and interface abruptness of these novel materials. It was found that the PE-PLD process can create stoichiometric thin films, the uniformity of which can be controlled by varying the power of the inductively coupled plasma. This technique showed a high deposition rate of ∼ 0.1 nm s −1 .

Optical emission spectroscopy (OES) of the magnetic dipole allowed O2(b1Σg +) to O2(X3Σg −) transition was investigated as a non-intrusive gas temperature diagnostic for E-mode and H-mode inductively coupled plasmas (ICP) in oxygen. It was compared to tunable diode laser absorption spectroscopy using Ar admixtures, and OES of the nitrogen Second Positive System with nitrogen admixtures. O2 OES provided accurate results for the E-mode ICP, 400–600 K for powers of 100–300 W, but in H-mode the method was unsuitable probably because of excitation of O2(b1Σg +) by metastable atomic oxygen. Rotational temperatures were measured, using N2 OES with N2 admixtures, for pulsed operation of the ICP with a 30 ms pulse duration and 15% duty cycle. It took 1–3 ms before the steady-state rotational temperatures were achieved. In addition, a small variation of matching network settings affects the plasma ignition delay time by several ms.

No abstract