T. Kovacs

Suppression of low angle grain boundaries in seeded thick Si films recrystallized between SiO2 layers

We observe a marked suppression in the formation of low angle grain boundaries (sub‐boundaries) during the graphite strip heater recrystallization of thick Si films over buried islands of SiO2. For 27‐μm‐thick Si films, areas exceeding 1×1 mm2 have been recrystallized on SiO2 which are completely free of grain boundaries and sub‐boundaries, but which contain dislocations in other configurations. Moreover, we find the density of these remaining dislocations to be much reduced near the upper and lower SiO2 interfaces.

Si‐on‐insulator films of high crystal perfection by zone melting under a SiO2 cap provided with vent openings

We observe a marked improvement in the crystal perfection of zone melted thick Si‐on‐insulator films that were prepared for melt processing by etching an array of openings in the SiO2 capping layer. Chemical defect etching and Rutherford backscattering measurements reflect this improvement, which we believe is due to the creation of new venting paths that reduce the level of excess dissolved SiO2 in the molten Si before recrystallization.

Laser Induced Diffusion of Radioactive As into Si

A high efficiency technique for incorporating As or other high volatility elements into Si and other semiconductors by laser pulse processing is described. By this method more than 80% of the As atoms painted onto a Si surface were made to relocate onto substitutional sites in the 73 Si crystal. Mossbauer analysis of laser diffused As atoms in a Ge crystal indicates that although the final As sites are >97% substitutional, the majority are associated with one or more defects not seen in conventionally diffused material.

Radiation overload warning system for Geiger-Müller detectors

Abstract We call attention to the characteristic that common Geiger-Muller detectors can give false safe readings when actually under dangerous radiation overload. We describe inexpensive circuitry which reliably warns the operator of this condition.