Admittance spectroscopy and capacitance dispersion of AlGaN/GaN hetero-structures

Admittance spectroscopy of pristine AlGaN/GaN metal-semiconductor interface reveals the distributed trap activation energy in the order of 0.24 eV by mercury probe capacitance-voltage (C-V) measurements. The trap densities of states (D_it) of these traps were extracted in the range of ~1.9×10¹² eV^-1cm^-2 with the reverse bias voltage ranging from -5 Volts to 0 Volt. A very good fitting of admittance spectra (G/ω) was obtained by using the time constants of these traps. The dispersion in the capacitance was corrected to obtain an accurate depth profile of the hetero-structures.