Deep Level Transient Spectroscopy (DLTS)

Description

Deep Level Transient Spectroscopy is a technique based on the measurements of a junction’s (p-n or Schottky type) capacitance relaxation kinetics after applying a voltage pulse. The DLTS measurement is performed within a monotonic temperature change. As a result one obtains a spectrum, consisting of a series of peaks attributed to a given defect level in the structure. A digital DLTS variant – Laplace DLTS, which has one order of magnitude better resolution compared to classical one, allows in turn for a precise separation of the levels introduced by defects having similar origin and activation energy. This is impossible in a classical DLTS approach.

Specification

• Optical nitrogen cryostat or helium cryostat operating in tandem with closed-circuit helium micro cooler
• Lakeshore 332 temperature controller
• Digital capacitance meter Boonton7200, f = 1 MHz
• Maximal sample dimensions: 2mm´2mm

Applications

Using a DLTS technique or its variants one can analyze defect levels in the examined structure. The basic parameters that can be collected from  DLTS are: defect activation energy, trap concentration and a capture cross-section. Due to its simplicity, DLTS method is efficiently applied to a defect structure examination in semiconductors. Understanding their defect nature allows to construct advanced devices with the desired optical and electrical parameters.