Bulletin of the American Physical Society
2023 APS March Meeting
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session G41: Defects in Nitrides
11:30 AM–2:06 PM,
Tuesday, March 7, 2023
Room: Room 319
Sponsoring
Unit:
DMP
Chair: Suraj Cheema, University of California, Berkeley
Abstract: G41.00001 : Optical Absorption of point defects in AlN crystals as measured by photo-induced electron paramagnetic resonance
11:30 AM–12:06 PM
Presenter:
Mary Ellen Zvanut
(University of Alabama at Birmingham)
Author:
Mary Ellen Zvanut
(University of Alabama at Birmingham)
An extensive series of measurements by others indicates that the main EPR signal studied here is due to an axial Al centered on a nitrogen site [1]. The spectrum has been assigned to a nitrogen vacancy (VN0) or substitutional oxygen (ON0). However, recognizing that the resonance may be caused by the presence of any impurity with nearly 0 nuclear spin, our optically induced EPR studies suggest a third alternative. By illuminating the sample at room temperature, we show that the EPR signal is activated at 3.8 eV and subsequently quenched at about 1.8 eV. Neither threshold is consistent with an assignment as a ON since oxygen is expected to be a shallow donor in AlN. While the 3.8 eV absorption threshold is reasonably close to that expected for VN, comparison with optical transitions reported in the literature, suggests that carbon substituting for nitrogen, CN0, agrees more closely with the optical and EPR data. Thus, by combining EPR directly with illumination, we suggest a reassignment of the EPR signal and support identification of the ~ 4 eV absorption threshold and predicted defect level. The talk will highlight the role of carbon in AlN and the potential limitations facing both optical and electronic applications.
[1] V.A. Soltamov et al, J. Appl. Phys. 107, 113515 (2010).
This work was supported as part of the Ultra Materials for a Resilient Energy Grid, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0021230.
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