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HL: Fachverband Halbleiterphysik
HL 37: Nitrides II – Designed properties and LED
HL 37.6: Vortrag
Donnerstag, 12. März 2026, 10:45–11:00, POT/0006
Nano-characterization of polarization-doped deep UV LED structures using highly spatially resolved cathodoluminescence spectroscopy — •E. Bäker1, F. Bertram1, G. Schmidt1, N. Dreyer1, J. Christen1, T. Kolbe2, S. Hagedorn2, H.K. Cho2, J. Rass2, S. Einfeldt2, and M. Weyers2 — 1Otto-von-Guericke-University Magdeburg, Germany — 2Ferdinand-Braun-Institut (FBH), Germany
AlGaN-based deep UV LEDs emitting below 250 nm are of great interest for many applications. Especially in the far-UVC, efficient p-doping poses major challenges, which can be effectively overcome by the concept of polarization doping. This study compares far-UVC LEDs with different AlGaN composition gradients used for polarization doping. The LEDs were grown by MOVPE on optimized AlN/sapphire templates. While the n-side of the diode uses conventional Si-doping, the p-side utilizes an AlGaN-layer with constant [Ga]-gradient. Diodes with different [Ga]-gradients but identical thicknesses are analyzed, with the Ga mole fraction increasing linearly from 0.02 to 0.45 and from 0.02 to 0.81, respectively. Using low temperature cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope, a nano-scale correlation of the optical properties with the real structure is obtained. Cross-sectional CL line scans show the different emission of the gradient layer. While the sample with the shallow gradient shows continuous emission spectral red-shift from 240 nm to 260 nm, the sample with the steep gradient shows an abrupt jump from 273 nm to 312 nm, indicating lattice relaxation.
Keywords: Cathodoluminescence; Scanning transmission electron microscopy; Deep UV LED; Polarization Doping