Deep Level Characteristics in n-GaN with Inductively Coupled Plasma Damage

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The effects of energetic ion-induced damage on deep traps in n-GaN have been investigated using deep level transient spectroscopy. The energetic ions were produced in an inductively coupled plasma reactive ion etching (ICP-RIE) system. The electrons captured at the trap levels E1 (0.25 eV) and E2 (0.62 eV), in a control sample, were found to depend logarithmically on the duration of the filling pulse, indicating a relationship to dislocations. The dramatic increase in the concentration of deep level E1 traps, as a function of etching-bias voltage, is thought to indicate the introduction of a VN-related complex. On the other hand, the concentration of deep level E2 traps shows an initial increase at an etching-bias of −50 V, followed by a decrease at higher etching-bias voltages. This trend was also observed in the room-temperature yellow luminescence spectra and x-ray photoelectron spectroscopy, which suggests that the deep level E2 is associated with point defects in the form of VGa-impurity complexes.