Semiconductor Research

High spatial resolution TRPL microscopy enables non destructive investigation of charge carrier dynamics in semiconductor materials and quantum well structures. The poster summarizes carrier diffusion imaging, power dependent TRPL, and spectrally resolved measurements, illustrating how spatial and temporal photoluminescence analysis reveals structure to photophysics relationships in complex semiconductor systems.

Time-resolved fluorescence spectroscopy and microscopy provide quantitative access to excited-state and charge carrier dynamics in semiconductor materials. This application note summarizes lifetime-based methods such as TRPL, FLIM, and correlation spectroscopy, demonstrating how temporal and spatial resolution reveal recombination, diffusion, and mobility-related processes beyond steady-state measurements.

Time-resolved emission spectra (TRES) were used to separate charge carrier dynamics in a GaAsP quantum well heterostructure. Emission peaks at 650 nm, 735 nm, and 860 nm are assigned to the Al₀.₄Ga₀.₆As barrier, the GaAsP quantum well, and the n-GaAs layer and the GaAs substrate. Layer-specific lifetimes reveal distinct recombination dynamics within the multilayer system.

Excitation spectra were recorded for three emission channels of a quantum well wafer: 650 nm (Al₀.₄Ga₀.₆As barrier, blue), 735 nm (GaAsP quantum well, light green), and 860 nm (n-GaAs layer and GaAs substrate, dark green). A dip around 650 nm in the 735 nm channel indicates barrier–well interaction, while the rise in the 860 nm channel correlates with the absorption edge of the barrier at wavelengths longer than the barrier band gap. Colored bands mark the layer band gaps.

Following localized excitation with a pulsed 440 nm laser, TRPL imaging was used to monitor charge carrier diffusion in a semiconductor sample. Lifetimes extracted from regions of interest (ROI) with increasing distance from the excitation spot increase systematically, reflecting the additional time required for carriers to diffuse before recombination. This spatially resolved delay provides direct access to diffusion-related transport processes.