The generation of microdefects in FZ-silicon during long-time high-temperature processing, necessary for tho production of power devices, has been investigated by etching techniques and transmission electron microscopy. The results prove the defects t o be large precipitates, which may generate dislocations and stacking faults. The

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Infrarotspannungsoptische Untersuchungen an Halbleitereinkris tallenDer piezooptische Effekt in Kristallen, speziell in Kristallen der Klassen m3m und 33 m des regulciren Systems wird erlciutert. Unter Beachtung der Symmetrieeigenschaften wird eine Methode zur Messung der Spennungsdoppelbrechungskonstanten (qI1 -q12) und q,, an einer einzigen Materialprobe vorgeschlagen und an Siund GaAs-Einkristallen praktisch angewendet. Zur Messung der Spannungsdoppelbrechungskonstanten wurde eine Apparatur entwickelt, die mit grol3er Genauigkeit quantitative Bestimmungen erlaubt. Zur Probenpriiparation wurden mehrere Verfahren untersucht.Die Messungen an verschiedenen Si-bzw. GaAs-Einkristallen ergaben unterschiedliche spannungsoptische Werte, die mit den bisher in der Literatur angegebelien Werten verglichen werden. Es wird gezeigt, daB der Begriff ,,spannungsoptische Konstante" nicht ale Materialkonstante, sondern als kristallindividueller Wert aufgefaBt werden muB. Unter Verwendung der gemessenen spannungsoptischen Werte werden die Restspannungen in kompakten Einkristalleri aus Doppelbrechungsmessungen an dicken Scheiben rekonstruiert.The piezooptic effect in crystals is explained, in particular for cubic classes m3m and 33m. Taking in consideration the properties of symmetry, a method is proposed for measuring the piezobirefringence constants (qll-q12) and q4* in a single sample only, and its application to Si-and GaAs-single crystals is shown. A device was constructed for exact measurement of the piezobirefringence constants. Some methods for the preparation of the samples were examined.The measurements on different Si-and GaAs-single crystals lead to different photoelastic values. These values are discussed in comparision to values published up to now in the literature. It is shown that the terminus ,,photoelastic constant'' cannot be used in the meaning of material constant, because these values are specific for every crystal. Taking into consideration the photoelastic values measured the residual stresses in crystal ingots are reconstructed by birefringence measurements on thick slices.

Process‐induced crystal defects (point defects and extended defects) in completely processed transistor samples of floating zone silicon have been investigated by TEM analysis and DLTS measurements. It was possible to demonstrate that the lifetime of these samples is determined by the introduction of copper during the long‐time processing of the wafers. The predominant crystal defects within the wafer volume were found to be circular monolayers of copper silicide which due to their appearance could be easily confounded with stacking faults.

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