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HL: Fachverband Halbleiterphysik
HL 1: Nitrides: Preparation and characterization I
HL 1.12: Talk
Monday, March 18, 2024, 12:45–13:00, EW 015
Highly resolved cathodoluminescence spectra of N-polar homoepitaxial AlN — •Domenik Spallek1, Gwénolé Jacopin2, Len van Deurzen3, Jashan Singhal3, Jimy Encomendero3, Oliver Brandt1, Debdeep Jena3, and Jonas Lähnemann3 — 1Paul-Drude-Institut, Berlin, Germany — 2Institute Néel, CNRS, Grenoble, France — 3Cornell University, Ithaca, New York, USA
As a semiconductor with an ultra-wide band gap, AlN is an interesting material for applications in optoelectronic devices such as UV-LEDs. Additionally, its high thermal conductivity and breakdown field are advantageous for applications in high power electronics. High quality AlN layers of either Al or N polarity can be grown homoepitaxially on commercial substrates by molecular beam epitaxy (MBE) [1]. Besides serving as potential basis for device structures, the low point defect and dislocation densities result in high luminous efficiencies, which makes such layers a suitable platform for comprehensive investigation of their fundamental excitonic emission.
We focus on an N-polar AlN layer and present near-band-edge cathodoluminescence spectra as a function of temperature, as well as for different measurement geometries. An improved spectral resolution uncovers additional emission lines compared with Ref. 1. The various emission lines can be assigned to free excitons with different symmetries and defect-bound states of different origin, as well as their phonon replicas. Thus, this study contributes to the resolution of controversies in the attribution of excitonic emission lines in AlN.
[1] van Deurzen et al., APL Mater. 11, 081109 (2023)
Keywords: cathodoluminescence spectroscopy; AlN; ultra-wide bandgap; excitonic emission