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The integral and spectral cathodoluminescence (CL) properties of grain-boundary zones in positive-temperaturecoefficient-type barium titanate ceramics were investigated with respect to typical sintering parameters in the spectral range 300 to 1800 nm at room temperature. Spatially resolved CL micrographs for the wavelength range 300 to 850 nm show dark grain-boundary zones and light grain interiors. Corresponding micrographs for the infrared wavelength range 800 to 1800 nm show just the opposite CL contrast. The CL properties of the grain-boundary zone can be correlated to doubly ionized barium vacancies. Therefore, grain-boundary zones which are visible in integral CL images of both wavelength ranges represent the theoretically predicted grain-boundary zone of high barium vacancy concentrations. The width of these grain-boundary zones varies characteristically with sintering time and cooling rate. Additional measurements of the electrical conductivity of the specimens confirmed the theoretically assumed correlation between grain-boundary-zone width and electrical resistance of the samples.

The grain cathodoluminescence (CL) properties of bariumtitannte ceramics, sintered at, different oxygen partial pressures are systematically investigated. The spectra are found to be composed of different bands, the intensities of which depends strongly on the specimen temperature and on the oxygen partial pressure of the ambient atmosphere during the sintering process. By fitting the obtained spectra with superposed Gaussian curves i t is shown that the involved recombination processes can be satisfactorily explained within the configurational coordinate model. Furthermore i t is possible to trace back the observed electronic transitions to vacancy luminescence, corroborating existing theories on band schemes, and on dependences of vacancy concentrations on oxygen partial pressure during the sintering. In this way the observed bands may be assigned to transitions in t h e energy gap of BaTiO,.Die Kat,hodolumineszenzeigenschaften von Kristalliten in Bariumtitanat-Keramiken, die unter verschiedenen Sauerstoffpartialdriicken gesintert werden, werden systematisch untersucht. Es kann gezeigt werden, daB die Spektren aus verschiedenen Banden bestehen, deren Intensitliten starke Abhangigkeit von der Probentemperatur und voni Sauerstoffpartialdruck der Sinterat,mosphare aufweisen. Durch das Anpassen der erhaltenen Spektren mit superponierten GauBkurven wird gezeigt, daB die beteiligten Rekombinationsprozesse mit dem Konfigurationskoordinat,en-Model1 erklart werden konnen. Ferner ist es moglich, die beobachteten elektronischen tfbergange auf Leerstellenlumineszenz zuriickzufuhren und bestehende Theorien uber Bandschemata und Abhangigkeiten von Leerstellenkonzentrationen vom Sauerstoffpartialdruck wahrend des Sinterns zu untermauern. Auf diese Weise kann eine Zuordnung der beobachteten Bander zu tfbergangen in der verbotenen Zone von BaTiO, erfolgen.KommandantenstraDe 60, D-4100 Duisburg 1, FRG. 9* 132 G. KOSCHEK and E. KUBALEH Fig. 1. Secondary electron image of the investigated BTC samples. a) specimen 1, sintered in air for 10 h a t 1350 "C; b) specimen 2, sintered in H,/N, a t 1350 "C for 10 h

A new contactless device internal test technique is introduced based on a scanning force microscope enabling dynamic voltage contrast within passivated integrated circuits. A spatial resolution below 500 nm and voltage resolution down to voltages of 0.2 V amplitude are achieved. For the first time static voltage contrast obtained with the scanning force microscope is shown on passivated integrated circuits. Potential and limits of this test technique are discussed.