PERMEABLE BASE TRANSISTOR FABRICATION BY SELECTIVE EPITAXIAL-GROWTH OF SILICON ON A SUBMICROMETER WSI2 GRID

We report the epitaxial growth of silicon on a tungsten disilicide grating using a rapid thermal processing, low-pressure chemical vapor deposition reactor. Results indicate that silicon grows selectively on the patterned Si/WSi2 structure, irrespective of the grating periodicity (from 0.6 μm up to several tens of microns). The epitaxial growth of silicon is shown to proceed two dimensionally on the Si surface and laterally over the WSi 2 lines without any reaction with the underlying WSi2 grid. Preliminary electrical measurements of the Si/WSi2/Si overgrown permeable base transistor thus fabricated are presented, showing current densities Jmax of up to 6000 A/cm2 and transconductances gm of 5 mS/mm.