Site of Acoustic Signal Generation by Chopped Electron Beam (Electron-Acoustic Microscopy).

The junction between the base and the collector of an npn Si transistor-chip was exposed by angle lapping and microscopically observed. The specimen thus prepared under various bias conditions was observed by SEM and electron-acoustic microscopy (EAM). The results are as follows. (1) The site of acoustic signal generation by irradiation of the chopped electron beam remains unchanged under varying bias voltages. (2) The amplitude of the acoustic signal changes under various bias conditions. (3) The acoustic signal- and electron-beam-induced current signals nearly correspond to each other under bias applications, but they are clearly different signal modes. The mechanism of acoustic signal generation is suggested and discussed. [ABSTRACT FROM PUBLISHER]