Meaning
Analytical techniques measure the capacitance or current transients of a semiconductor junction to identify defect states. Scientists utilize deep level transient spectroscopy to detect and characterize impurities that create traps in the bandgap. These traps can reduce the carrier lifetime and efficiency of the device.
Trapping Analysis
Thermal emission rates of captured carriers provide information about the energy level and capture cross-section of the defect. By sweeping the temperature of the sample, deep level transient spectroscopy produces a spectrum where each peak corresponds to a specific trap. This information allows engineers to identify the source of contamination in the production line.
Characterization Protocol
Formal testing must follow the standards established by the Ministry of Industry and Information Technology for semiconductor material purity. The deep level transient spectroscopy process is a requirement for the qualification of new silicon carbide or gallium nitride suppliers. During this procedure, the laboratory must document the temperature range, the pulse width and the frequency of the measurement.
This data is archived to ensure that every batch of material meets the rigorous stability requirements for high-voltage power modules used in heavy industry.
Quality Assessment
Final reports from accredited laboratories include a density map of all detected traps. A high level of defects found through deep level transient spectroscopy indicates a failure in the crystal growth or doping process. This assessment is used to decide the commercial grade of the wafer.
