Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 5: Optical Properties I

HL 5.6: Talk

Monday, March 18, 2024, 11:00–11:15, EW 561

Carrier generation and diffusion in Ga(As,Sb) nanowires probed by cathodoluminescence spectroscopy — •Mikel Gómez Ruiz¹, Vladimir Kaganer¹, Akhil Ajay², Hyowon Jeong², Gregor Koblmüller², Oliver Brandt¹, and Jonas Lähnemann¹ — ¹Paul-Drude-Institut für Festkörperelektronik, Germany — ²Walter Schottky Institut, School of Natural Sciences, Technical University of Munich (TUM)

Semiconductor nanowire (NW) structures emitting at wavelengths used for optical telecommunications are attractive for the integration on silicon-on-insulator waveguides. Here, we study Ga(As,Sb) NWs with a lower bandgap (In,Ga)As insertion on a microscopic scale by cathodoluminescence (CL) spectroscopy to understand the charge carrier transfer to and the recombination in the insertion. In our CL experiments the electron beam, and thus the volume in which electron-hole pairs are generated, is scanned along the axis of the NW. After their generation and diffusion, the carriers recombine either in the Ga(As,Sb) segment or in the (In,Ga)As insertion, giving rise to spectrally distinct CL bands. The intensity profiles of both emission bands are recorded as a function of the beam position. Although the (In,Ga)As insertion is only about 20 nm long, the corresponding CL band can be observed over a length of more than 400 nm under high excitation conditions. The evolution of these profiles with temperature is studied to determine the diffusion length in the Ga(As,Sb) NW using a model that includes the temperature-dependent generation volume and the diffusion of the cathodogenerated carriers.

Keywords: Carrier diffusion; Cathodoluminescence; Nanowires; Heterostructures