There is an extension to DLTS known as a high resolution Laplace transform DLTS (LDLTS). Laplace DLTS is an isothermal technique in which the capacitance transients are digitized and averaged at a fixed temperature. Then the defect emission rates are obtained with a use of numerical methods being equivalent to the inverse Laplace transformation. The obtained emission rates are presented as a spectral plot. The main advantage of Laplace DLTS in comparison to conventional DLTS is the substantial increase in energy resolution understood here as an ability to distinguish very similar signals.
Laplace DLTS in combination with uniaxial stress results in a splitting of the defect energy level. Assuming a random distribution of defects in non-equivalent orientations, the number of split lines and their intensity ratios reflect the symmetry class of the given
defect.
Application of LDLTS to MOS capacitors needs device polarization voltages in a range where the Fermi level extrapolated from semiconductor to the semiconductor-oxide interface intersects this interface within the semiconductor bandgap range. The electronic interface states present at this interface can trap carriers similarly to defects described above. If their occupancy with electrons or holes is disturbed by a small voltage pulse then the device capacitance recovers after the pulse to its initial value as the interface states start to emit carriers. This recovery process can be analyzed with the LDLTS method for different device polarization voltages. Such a procedure allows to obtain the energy state distribution of the interface electronic states at the semiconductor-oxide (or dielectric) interfaces.