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Main Title: Excited states of neutral donor bound excitons in GaN
Author(s): Callsen, Gordon
Kure, Thomas
Wagner, Markus R.
Butté, Raphael
Grandjean, Nicolas
Type: Article
Abstract: We investigate the excited states of a neutral donor bound exciton (D0X) in bulk GaN by means of high-resolution, polychromatic photoluminescence excitation (PLE) spectroscopy. The optically most prominent donor in our sample is silicon accompanied by only a minor contribution of oxygen—the key for an unambiguous assignment of excited states. Consequently, we can observe a multitude of Si0X-related excitation channels with linewidths down to 200 μeV. Two groups of excitation channels are identified, belonging either to rotational-vibrational or electronic excited states of the hole in the Si0X complex. Such identification is achieved by modeling the excited states based on the equations of motion for a Kratzer potential, taking into account the particularly large anisotropy of effective hole masses in GaN. Furthermore, several ground- and excited states of the exciton-polaritons and the dominant bound exciton are observed in the photoluminescence (PL) and PLE spectra, facilitating an estimate of the associated complex binding energies. Our data clearly show that great care must be taken if only PL spectra of D0X centers in GaN are analyzed. Every PL feature we observe at higher emission energies with regard to the Si0X ground state corresponds to an excited state. Hence, any unambiguous peak identification renders PLE spectra highly valuable, as important spectral features are obscured in common PL spectra. Here, GaN represents a particular case among the wide-bandgap, wurtzite semiconductors, as comparably low localization energies for common D0X centers are usually paired with large emission linewidths and the prominent optical signature of exciton-polaritons, making the sole analysis of PL spectra a challenging task.
Subject(s): GaN
polychromatic photoluminescence excitation
excited states
Issue Date: 5-Jun-2018
Date Available: 25-Feb-2020
Language Code: en
DDC Class: 530 Physik
Sponsor/Funder: EC/H2020/749565/EU/Heat Transport and its Effects on the Performance of Nanostructured, Photonic Materials/PhotoHeatEffect
DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelemente
Journal Title: Journal of Applied Physics
Publisher: American Institute of Physics (AIP)
Volume: 123
Issue: 21
Article Number: 215702
Publisher DOI: 10.1063/1.5028370
EISSN: 1089-7550
ISSN: 0021-8979
TU Affiliation(s): Fak. 2 Mathematik und Naturwissenschaften » Inst. Festkörperphysik » FG Optische Charakterisierung von Halbleitern
Appears in Collections:Technische Universität Berlin » Publications

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