Excess low frequency noises in some electronic materials and components
We devised burst noise eliminating equipment and characterized the 1/f and burst noise in some electronic materials, components, electric contacts and bipolar transistors. The burst-eliminated noise spectrum is the 1/f type. The noise intensity is proportional to the square of the current and to the fifth power of the contact resistance. This contact resistance dependence of the noise is analyzed with the constriction resistance of the contact surface material. The measured results are also shown in the amplitude and phase fluctuations in the transistor collector current. They are also of 1/f type and correlate each other. On the other hand, we did not find this correlation in another transistor with burst noise. Hence, the 1/f fluctuation is considered to be due to diffusion or mobility fluctuation and the burst noise is not due to the diffusion process in the solid.
1/f Noise in Metal Contacts and Granular Resistors
To measure the current noise in metal contacts and granular resistors, we arranged a noise measuring system with a switched-capacitor filter. The samples are crossbar contacts and grphite thick-film resistors. All noise spectra are the 1/f type. The noise of crossbar contacts and thick-film resistors increases in proportion to the fifth and third power of the resistance, respectively. A model for the noise of metal contacts and granular resistors is proposed. It is based on the spontaneous fluctuation of temperature of the small Conducting spots between metal surfaces and granular boundaries, respectively. The results of the analysis are qualitatively in agreement with those of measurement.
Use of laser scanning confocal microscopy for morphological taxonomy and the potential for digital type specimens (e-types)
The use of laser scanning confocal microscopy (LSCM) for creating taxonomic descriptions of copepods is investigated. A new technique is described, which employs a contour filter to process digital LSCM images, allowing taxonomic information to be quickly and accu- rately distilled into a simple illustration. LSCM allows the imaging of whole specimens, which can be rotated and viewed from any angle—a major benefit over light microscopy. Using this tech- nique, it is suggested that taxonomic descriptions can be rapidly produced in a fraction of the time required to produce similar descriptions using traditional light microscopy and hand drawing techniques. Good staining of specimens is, however, essential to produce accurate descriptions and more research is required in this area. The use of LSCM for morphological taxonomy shows great potential, not only for producing taxonomic descriptions, but also providing a comple - mentary adjunct to traditional type specimens in the form of 3D digital 'e-types' deposited in recognised international databases.