Properties of carrier traps in diode and RRAM devices via DLTS*

Defects and impurities are electrically active deformities in periodic lattice and change the properties of the materials. Active defects work as a charge carrier traps and occupy energy levels in the energy band gap, consequently change the electrical properties of the material. Deep Level Transient Spectroscopy (DLTS) is a powerful technology for the detection and identification of electrically active defects (known as traps) in semiconductors. It is a method to determine the energy levels via time dependent capacitance measurement in the bandgap and capturing cross sections of deep level traps in a semiconductor. In DLTS a bias voltage is applied to fill the traps with charge carriers and returned to normal bias, the traps will empty over time and changes the device’s capacitance. The behavior of transient capacitance over a range of different temperatures reveals traps position and properties.

An IN4007 commercial diode was used to calibrate the system with the temperature and appropriate fill pulse settings. The measurement was analyzed using rate windows analysis or transient fits. DLTS and IVT measurements on the IN4007 and Si/NiFeOxide/Au devices will be discussed.