Extended radio emission and its relation to parent galaxy properties is briefly reviewed. Our current understanding of the relation between absolute radio and optical luminosity, radio morphology and linear size is discussed. The impact of radio jets on dense cluster cores is discussed using M87 as an example. Finally, the relation of AGN's to star-bursting galaxies at high redshift is considered.

We present experimental results showing that Cr/p+/V amorphous silicon memory structures at room temperature exhibit step-like current-voltage characteristics associated with discrete, non-random resistance values. The resistance values observed are ∼26kΩ/i where i is an integer or half integer. The low bias current-voltage characteristics prior to the first step suggest that conduction in this regime is governed by tunneling across a region having very small dimensions, of the order of ∼5-7 Å, and having a diameter ∼30-50 Å.

The ac conductivities of non-volatile analogue memory states are measured in electro-formed Cr/p+/V amorphous silicon structures for a broad frequency range (from 0.1 Hz to 32 MHz). The results suggest that the memory action is associated with electronic processes.

In this paper we report the role of the a-Si:H on the electrical behaviour of Metal/ a-Si:H / Metal memory devices. We have investigated layers deposited at 250°C by the glow discharge method with various doping concentrations, from undoped up to 104vppm of either diborane or phosphine in silane. We have found that the a-Si:H layer affects the initial forming process and the subsequent OFF state resistance. The hydrogen contents of the films have been measured and are found to correlate, for the p-type samples, with the forming voltage.

ABSTRACT.: a-Si:H p+-n-i devices, after a once only forming process, switch between two distinct states, both of which are memory states, and are electrically programmable with pulses in the nanosecond range with at least a 1 million cycle endurance. They are known to be non-volatile memory states which persist for long periods. This paper examines the nature of this non-volatility by looking at the effects of time, temperature, bias and radiation. It is found that these digital memory states persist with no change in state for at least four years under zero bias, and that they can withstand high temperatures both under bias and at zero bias. This and a resistance to radiation and a space environment shows that a mechanism of charge storage is unlikely and that they may have applications in hostile environments. The reason for such stability is unclear, but may be associated with the incorporation and distribution of metal in the filamentary region.

We present experimental results showing that the ON state of amorphous silicon memory structures exhibits ballistic electron transport associated with a quantised resistance, h/2ie2, where i is the number of occupied one dimensional conducting channels (sub-bands) and the spin degeneracy is two (in the case when no magnetic field is applied). Conduction in the memory ON state is restricted to a narrow conducting channel through which the electrons can travel ballistically i.e. no collisions occur. As the applied voltage is increased, the width of the conducting channel is broadened. This results in additional conducting channels (sub-bands) passing through the Fermi energy and consequently the resistance drops by quantised values. In the presence of a magnetic field additional steps occur corresponding to the split levels at values of h/2(i + ½)e2. A particular feature of this quantised resistance is that the effect can be observed at relatively high temperatures effect can be observed at relatively high temperatures (from 4.2 K up to ∼190K).