Laser-assisted atom probe analysis of sol-gel silica layers.

Semi-conducting nanocrystals embedded in a non-conducting matrix of silicate glass may be used as non-volatile data storage device. Structures of silicate glasses are conveniently produced by a sol-gel process, which offers the possibility to coat tip-shaped substrates with a silica layer. The study presents first results of their local chemical analysis by laser-assisted atom probe. Till date the exact mechanisms of laser pulsing are still controversial. But it is common sense that there is an at least considerable heating effect on the tip, which leads to a short temperature rise and a prolonged cooling period in materials of low heat conductivity. This effect alters the shape of mass peaks and is examined here using a one-dimensional model of heat transport.