Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 10: Nitrides

HL 10.13: Vortrag

Montag, 5. September 2022, 18:15–18:30, H34

Pump-probe studies with varying excitation wavelengths applied for GaInN/GaN single quantum wells — •Malte Schrader, Rodrigo De Vasconcellos Lourenco, Heiko Bremers, Uwe Rossow, and Andreas Hangleiter — Institut für Angewandte Physik & Laboratory for Emerging Nanometrology, Technische Universität Braunschweig, Germany

The goal of this study is to characterize the ultra-fast carrier dynamics in c-plane GaInN/GaN single quantum wells (SQWs). To make transmission experiments possible the samples were grown on double-side polished sapphire by MOVPE. Furthermore we use time-resolved photoluminescence (TRPL) to measure the radiative and non-radiative carrier lifetimes of the samples from 5 K up to 300 K. By using a transmission-mode degenerate pump-probe technique at 300 K the generated state occupation in the SQW can be observed directly. Different excitation wavelengths produced using an optical parametric amplifier provided pulses of nominal 35 fs duration.

We observe carrier lifetimes at room temperature in the low ns range by TRPL, which are strongly impacted by nonradiative processes. Pump-probe at 300 K gives a fast characteristic relaxation time in the low ps range and a slower component associated with the decay observed in TRPL. This indicates that a fast initial non-equilibrium relaxation is followed by a component representing recombination of a quasi-equilibrium carrier ensemble. A surprising observation is the relatively slow relaxation time of a few ps, which one would rather expect to be in the femtosecond range.