The open-tube diffusion of Sn in GaAs and Zn in InP and InGaAs from spin-on films acting both as solid diffusion sources and as surface passivators is reviewed. Technological processes are described which lead to layers with reproducible, homogeneous properties necessary for device applications. The diffusion models which quantitatively predict the diffusion results are discussed. Experimental results are given showing the influence of film composition, diffusion temperature and time, and substrate properties, on surface morphology, carrier concentration and concentration profile and on carrier mobility. Applications of the process to highly doped, low resistivity contact layers, highly doped p+ gate layers and n-doped FET channels are demonstrated. Finally the potential use of doping from spin-on film instead of or in addition to existing doping processes (e.g. ion implantation) is discussed. It is concluded that this process adds a further degree of flexibility to the technology of III-V semiconductor compounds.

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Absfracf. The setting of controls of radioactive waste discharges fmm the major nuclear sites in England is a statutory responsibility of the Minister of Agriculiure, Fisheries and Food acting jointly with the Chief Inspector of Her Majesty's Inspectorate of Pollution, within the terms of the Radioactive Substances Act 1960 as amended by the Environmental Protection Act 1990. MAFFs technical responsibilities under the Act are divided between the Food Safety (Radiation) Unit, which is responsible for terrestrial exposure pathways, and the Fisheries Radiological Inspectorate, which is responsible for aquatic exposure pathways. Both groups operate in a similar way and their work can be considered to fall into four main areas. First, the discharge routes. important isotopes, exposure pathways and doses to the public are considered. Second, the adequacy of discharge controls is monitored by the inspection of plant operations and site records, and by MAFFs supervision of an environmental monitoring programme by the polluter. Third. an independent 'che& monitoring programme is carried out on the environmental impact of discharges. Fourth. there is a complementary research programme involving Specific projects designed to support monitoring and assessments methodology. These include duplicate diel surveys, whole body monitoring. gut transfer studies and the use of thermoluminescent dosemeters, as well as studies into environmental transfer processes and the development of analytical techniques.This systematic approach is shown to protect members of the public from any effects of radioactive waste dischaqes into the terrestrial and aquatic environments.