Deep-level transient spectroscopy using low-frequency capacitance measurements

The deep-level transient spectroscopy (DLTS) system is fabricated using low-frequency capacitance measurements and is applied to GaN thin layers to characterize electron traps. The frequency dependence of the capacitance gives the capacitance measurement frequency of 10 kHz in DLTS for the Schottky diodes fabricated on 1-μm-thick Si-doped GaN layers due to the high series resistance. DLTS using W-kHz capacitance measurements reveals three electron traps with the energy levels of E_c - 0.23, E_c - 0.31 and E_c -0.61 eV in addition to the broader signals in the temperature range from 350 to 500 K. The concentrations of these traps are found to be in the range of 10¹⁴ cm^-3.