Installation for measuring surface density states in semiconductors by the spectroscopy of photoemission quantum yield

A facility for measuring surface density states in superhigh vaccuum by spectral dependence of photoemission quantum yield is described. The facility comprises a vacuum chamber with devices providing measurement of photoemission characteristics and CAMAC crate for communication of analytical instruments with computers. For measurements a sample fixed on a universal manipulator is transferred to the multiplier inlet and it is exposed to light from a monochromator. Radiation power makes up 10sup(-6) W at 1 mm gaps at the inlet and outlet of the monochromator. Control of the experiment, data acquisition and processing were conducted by means of a computer. Spectrum of n- GaAs surface density states activated by cesium and oxygen is given as an example