Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 1: Nitrides: Preparation and characterization I
HL 1.3: Vortrag
Montag, 18. März 2024, 10:00–10:15, EW 015
Time-resolved cathodoluminescence spectroscopy of oxygen related defects in AlN layers — •Barbara Szafranski, Lukas Peters, Andreas Waag, and Tobias Voss — Institute of Semiconductor Technology, Braunschweig University of Technology, Germany
High temperature annealing (HTA) of sputtered AlN leads to a substantial improvement of the crystal quality. However, during the annealing process, a large number of point defects like oxygen is introduced. Oxygen has a double-edged role during HTA.
We therefore analyzed oxygen defects in AlN layers with cathodoluminescence (CL) spectroscopy. The 350 nm thick AlN layers were treated with HTA at different temperatures. The process has been optimised to lead to very high crystal quality.
At room temperature, CL spectroscopy shows a broad (FWHM 650 meV) luminescence band centered at about 3.66 eV (340 nm), which we correlate with oxygen point defects. To study the charge carrier dynamics of these defects in AlN, time-resolved CL measurements have been performed. The defect related emission is characterized by a complex multiexponential decay with a fast component of about 1 ns and a slow component of tens to hundreds of nanoseconds. In agreement with Genji et al., we attribute the short decay time to the radiative transition from the conduction band-edge states to (VAl−2ON)1− and (VAl−ON)2− and the long decay times to trapping and detrapping processes of the charge carriers via shallow traps [1].
[1] Kumihiro Genji and Takashi Uchino, Appl. Phys. Lett. 109, 021113 (2016).
Keywords: AlN; oxygen defects; time-resolved cathodoluminescence