AN INEXPENSIVE STM CONVERSION TO A BEEM

Ballistic electron emission microscopy (BEEM) is a relatively new tech nique enabling spectroscopic investigation of subsurface interface str uctures and electronic properties. BEEM is a direct, nondamaging metho d with nanometer spatial resolution. In this paper, an inexpensive mod ification to a conventional scanning tunneling microscope, converting it to a BEEM, is presented. BEEM performance is significantly affected by the, preamplifier and the low-pass filter, which is used to improv e the signal-to-noise ratio. The system is tested on a thin Au metalli zation to (100) Si. (C) 1995 American Institute of Physics.