Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 24: Nitrides: Preparation and characterization I

HL 24.10: Vortrag

Mittwoch, 3. April 2019, 12:00–12:15, H31

Influence of Electron Beam Irradiation on the Emission Spectra of InGaN/GaN MQWs — •Hendrik Spende¹, Johannes Ledig², Christoph Margenfeld¹, Hergo-Heinrich Wehmann¹, and Andreas Waag¹ — ¹Institute of Semiconductor Technology and Laboratory for Emerging Nanometrology, Braunschweig University of Technology, 38106 Braunschweig — ²Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany

A scanning electron microscope equipped with a cathodoluminescence (CL) detection system is a powerful tool for investigating the optical properties of semiconductor microstructures with high spatial resolution. Due to the high kinetic energy of the probe, electrons are scattered and many electron-hole-pairs are generated in the material. As a result, the excitation and recombination rate inside the material are spatially inhomogeneous.

Here we analyze CL spectra of InGaN/AlGaN/GaN samples, each containing MQWs emitting at different wavelengths. By varying the electron beam energy, the electron penetration depth changes and thus the obtained CL signal gives insight into the excitation ratios and relative efficiencies of the different MQWs. We also observe an unexpected and persistent change in the room temperature CL emission of the samples, indicating electron beam induced changes in carrier dynamics within the active area. Electrochemical capacitance-voltage measurement profiles show changes in the active carrier concentration in irradiated regions. Both can be reset by thermal annealing, indicating that the irradiation changes crystal bonds or the charge of trap states.