Deep level transient spectroscopy in III-Nitrides: Decreasing the effects of series resistance

A modification of deep level transient spectroscopy which varies the measurement frequency from 10 kHz to 1 MHz and is based on commercially available inductance-capacitance-resistance meters and pulse generators was tested for GaN films and AlGaN/GaN high electron mobility transistor structures with various series resistances. It is demonstrated that the measured spectra at high and low frequency follow the well documented frequency dependences of the stationary capacitance and magnitude of the capacitance transient. Measurements at low frequency allow for accurate determination of the concentration of the traps and, in many cases, detect traps that cannot be observed in the high frequency measurements. This is particularly valuable in materials like GaN where series resistance effects can be significant. (C) 2015 American Vacuum Society.