Quasipersistent change in Hall sensitivity after illumination

A quasipersistent change in the magnetic sensitivity of nonplate-like Hall sensors after light exposure has been discovered. The recovery time constan t is about 10 min. The observed effect is very similar to the persistent ph otoconductivity (PPC) which has been described some time ago in silicon bul k material. Surprisingly, the new effect is about 1 order of magnitude stro nger than the PPC. The similar recovery behavior of both effects suggests a common origin in precipitated oxygen clusters in the active zone. The ampl itude of the variations is highly dependent on the cluster concentration in the substrate. The presented Hall sensors give a sensitive means to charac terize the oxygen-denuded zone in Czochralski wafers. (C) 2000 American Ins titute of Physics. [S0003-6951(00)03648-2].