  Experiments with electron or ion matter waves require a coherent,
monochromatic and long-term stable source with high brightness. These
requirements are best fulfilled by single atom tip (SAT) field emitters. The
performance of an iridium covered W(111) SAT is demonstrated and analyzed for
electrons in a biprism interferometer. Furthermore we characterize the emission
of the SAT in a separate field electron and field ion microscope and compare it
with other emitter types. A new method is presented to fabricate the
electrostatic charged biprism wire that separates and combines the matter wave.
In contrast to other biprism interferometers the source and the biprism size
are well defined within a few nanometers. The setup has direct applications in
ion interferometry and Aharonov-Bohm physics.
