A highly transmittive semiconductor base for ballistic electron emission microscopy

Ballistic electron emission spectroscopy and ballistic electron emission microscopy offer the unique possibility of probing subsurface quantum states. To improve the spectroscopic sensitivity, it is important to increase the amount of electrons, which are able to penetrate into the sample. In this work, we show that the transmission coefficient and the attenuation length of the base layer can be enhanced by more than one order of magnitude, if the commonly used thin metal film is replaced by a molecular beam epitaxy grown InAs layer. At low temperatures (T = 100 K), a passivated InAs layer yields an attenuation length in the order of 70-90 nm instead of 5 nm obtained on Au films. (C) 1998 American Institute of Physics. [S0003-6951(98)01235-2].