Laser absorption experiments are described to measure the radial sodium ground-state distribution in the positive column of a low-pressure Na-Ne discharge. The radial electron density distribution is obtained by combining the results with a particle balance. The electron densities at the tube axis ne(0) derived in this way are approximately a factor of 2.5 higher than the ones derived from a direct determination with Langmuir probes. Measuring the sodium profiles as a function of the distance to a probe reveals quantitatively the perturbative effect on the plasma of the glass capillary that supports the probe. This partly explains the observed discrepancy in ne(0). The electron temperature Te is deduced from the laser absorption data using the measured electrical conductivity of the plasma. This value of Te agrees very well with the value as measured with the probe.

The ionisation coefficient in Kr-Hg mixtures has been measured for E/n values between 2*10-20 V m2 and 2*10-18 V m2 and for a mercury atom fraction varying from 8*10-4 to 8*10-2. The experiments were performed with a parallel-plate apparatus in which the current is measured as a function of the plate separation at constant electric field. The ionisation coefficient was found to be a function of E/n and the mercury atom fraction only. The increase in the ionisation coefficient for small admixtures of mercury is mainly due to associative ionisation. From the experimental results the effective rate coefficient for excitation of the appropriate krypton states is obtained as a function of E/n, as well as the ratio of the rate coefficients for depopulation of these excited krypton states by nonionising collisions with krypton and ionising collisions with mercury atoms respectively.

A b s t r a c t The device characterisation and the ringoscillator performance of a high density half-micron CMOS process were studied. A novel recessed field isolation technology , twin retrograde wells, N + poly-silicon gate material and lightly doped drain structures for both the n-and p-channel devices were used in the device fabrication. The device properties and the ringoscillator performance will be presented.

The ionisation coefficient in mixtures of argon and krypton has been measured. From the results it is learned that for pressures above 2 kPa, ionisation processes occur through the interaction of highly excited argon states with ground state krypton atoms. Values are obtained for the rate coefficient for excitation of the highly excited argon states for E/n>100*10-21 V m2.