Physikalisches Kolloquium
PD Dr. Thomas Dittrich und Herr Dr. Steffen Fengler
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
Surface photovoltage spectroscopy of ultra-wide bandgap materials
Abstract:
The photoelectric characterization of electronically active defects over the entire bandgap is still challenging for ultra-wide bandgap materials, such as AlN, Ga2O3 and diamond. A mirrorless double prism monochromator is introduced as a light source for continuous illumination from the near infrared to the deep ultraviolet for photoelectric characterization of defect-related transitions. Surface photovoltage measurements have the advantage that they do not require contact preparation. Examples for the characterization of DC, AC (modulated) and AC (transient) will be shown for powders, crystals and layers. The analysis of effective absorption cross sections and the access to defects at buried interfaces will be demonstrated. Some information about very recent work and projects will be given in the outlook.
