Deep Level Transient Spectroscopy (DLTS) was
developed in 1974 by D.V. Lang [1] to investigate
energetically "deep" charge trapping levels in
semiconductor space charge structures, which
may be either pn junctions or Schottky barriers. It
utilizes the fact that the rf capacitance of the sample
(usually measured at 1 MHz under reverse
bias) depends on the charge state of deep levels
in the space charge region (SCR). In total depletion
approximation, the rf capacitance of a sample
having a homogeneous doping concentration is: