In previous papers it was shown that the electron mirror microscope can be used to investigate the details of the impurity distribution in silicon crystals (1 to 3).In the present note preliminary results on the drift of lithium ions along regions irradiated with 3 MeV electrons are given.were cut to obtain plates with approximate dimensions 4 x 3~2 mm3. After standard mechanical and chemical polishing and cleaning the lithium was diffused perpendicularly to the largest face which was a (111) plane. The diffusion was carried out at 350 C during about one minute. In this way a p-n junction was obtained. The side of the crystal into which lithium was diffused was irradiated with electrons from an accelerator. The arrangement for mounting the crystal during irradiations is shown on Fig. 1. To make possible the simultaneous observation of the drift process along irradiated and non-irradiated regions the crystal was bombarded through a metal plate with a slit having a width of 70 pm. As a result a narrow regionwithradiation defects intersecting the surface studied was obtained. During electron bombardment the crystal was kept at a temperature near 77 OK. The dose of electron radiation was such as to give about to 1018 radiation defectshm (vacancies and interstitials). The drift of lithium ions was carried out at a temperature of 80 OC and a voltage of 300 V was applied in the reverse direction. In some of the crystals the lithium was drifted also at room temperature.The investigated silicon crystals were p-type with a resistivity of 5OORcm. They 0 3 It has been found that the rate of the drift process is faster along irradiated regions. At 80 OC, for example, the mobility of lithium ions along regions with ra-8 pnysica

A new type of electron mirror microscope is described schematically. The microscope allows the observation of electrical micro‐fields on semiconductor surfaces in the temperature range 77 to 1300 °K. Preliminary results of observations on silicon surfaces at low temperatures are presented. It is suggested that the observed pictures can be interpreted in terms of surface fields resulting from the trapping of minority carriers. Results concerning impurity precipitation in silicon and germanium are also given.

Electron microscope mirror observations are made of surface microfields arising from lithium impurity segregations on silicon crystals. Rapid surface drift of the lithium ions is observed on dislocation areas. When the lithium impurity is partially evaporated from the crystal the surface becomes inhomogeneous. This is considered to be due to a difference between the rate of evaporat,ion from areas with, and without, defects. Local microfields with [B--Li+] ionic binding and their dissociation are also observed. Beobachtungen der Oberflachenmikrofelder, die durch Lithiumverunreinigungsabscheidungen auf Siliziumkristallen verursacht sind, werden mit Hilfe eines Elektronenspiegelmikroskops durchgefiihrt. I n Versetzungsebenen wird schnelle Oberflachendrift von Lithiumionen beobachtet. Wenn die Lithiumverunreinigung teilweise vom Kristall abgedampft wird, wird ein inhomogenes Bild der Oberflache erhalten. Das wird durch unterschiedliche Verdampfungsgeschwindigkeiten an den storstellenbehafteten und den storstellenfreien Oberflachenteilen erklart. Lokale Mikrofelder, die mit der Bildung von Ionenpaaren [B--Lit] und ihrer Dissoziation verbunden sind, werden ebenfalls beobachtet.