Thin silicon-on-insulator (SOI) layers of 0.5–2 µ m thickness are characterized by the microwave photoconductivity decay (µ-PCD) method with an N2 laser as the excitation source. The penetration depth of the N2 laser light is less than 0.1 µ m, and thus the excess carriers are excited only in the SOI layers. The measured recombination lifetime is sensitive to SOI thickness and interface properties, and thus the µ-PCD method can be used for characterization of the interface and observation of thickness variation. The surface (interface) recombination is considered as the dominant recombination mechanism.

Surface properties of ion-implanted silicon are investigated by the microwave photoconductivity decay method. The effective surface recombination velocity (S) is estimated by fitting of the experimental decay curve of excess carrier concentration with a theoretical decay curve. The results show that S is almost inversely proportional to the carrier concentration of the heavily doped layer formed by the ion-implantation for both types of high-low junction ( n+n, p+p). Thus the present method is a powerful tool for surface characterization.

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Furo −cho ， ChikUsa − kU， Nagoya 464 − 8603 Japan Recently ， regenerative medicine has been f()cused wlth stem cells that can regenerate the lost human tissues and organs ． To measure healthiness of ceUs non − invasively ， microwave atomic force microscope ( M − AFM ) which can measure electrical properties and topography of cells has been developed ． M − AFM probe was fabricated by forming a microwave tmnsmissioll line on the probe cant 且eveL We succeeded in measuring both the microwave response and the surface topography of drled mesenchymal stem cells after etha 皿01 dehydration by M −AFM with the probe ． As a result ， the change of microwave signals depending on the cell tissues was detected ．

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