Deep Level Transient Fourier Spectroscopy (DLTFS) and Isothermal Transient Spectroscopy (ITS) in vertical GaN-on-GaN Schottky barrier diodes

The paper explores the Deep Level Transient Fourier Spectroscopy (DLTFS) capabilities in characterizing electrically active traps in vertical GaN-on-GaN Schottky barrier diodes (SBDs). The capacitance-DLTFS (C-DLTFS) experiments reveal a prominent electron trap T2 at E-C - 0.56 eV with a density (N-T2) of 8 x 10(14) cm(-3) and a weak presence of another trap at E-C - 0.18 eV (T1) with N-T1 = 3.8 x 10(13) cm(-3) in the SBDs. The C-DLTFS acquired with two emission transients (T-E = 20.48 ms and 2.048 s) has resulted in identical trap signatures for T1 and T2. Due to the high N-T, the trap T2 at E-C - 0.56 eV is identified from the current-DLTFS (I-DLTFS) and thermally stimulated capacitance (TSCAP) measurements. Especially the TSCAP results indicate the carrier freeze-out temperature (T < 75 K) in the GaN material. Furthermore, the carrier emission kinetics of the trap T2 is evaluated by performing isothermal transient spectroscopy at a stabilized temperature. The capture time constant of T2 is estimated from the isothermal transients attained with shorter trap-filling pulse widths (<100 ns).