Overview
The time-resolved photoluminescence (TRPL) setup explores how the luminescence emitted by optically-excited samples varies with time, where the time period can be on the order of nano or picoseconds. Analysis of the ultrafast behaviour of light emitted from samples can reveal invaluable information regarding the recombination processes involved, including the lifetimes of the various transitions. The setup includes;
• Coherent Mira Ti:Sapphire laser – for excitation of the samples
• PicoQuant Picosecond Laser system – alternative excitation source
• Dual-stage Liquid Helium Cryostat – for cooling samples down to 4 K
• Hamamatsu C5680 Series Universal Streak Camera – for temporal and spatial analysis of the light pulse
Main Features:
• Up to 2 ps temporal resolution
• High excitation power densities (15 kW/cm2)
• 4 K – 350 K temperature range
• TE cooled photocathode, 300 nm - 1600 nm detection range
• Simultaneous measurement of light intensity on temporal and spatial (wavelength) axes - time-resolved spectroscopy
• Ultra-high sensitivity - single photon detection
The TRPL setup is part of the PDD's Photoluminescence Spectroscopy Laboratory. Click here for a PDF brochure.
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Location:
PDD, CIT
Case Study
Antimonide-based compounds have promise for the next generation of optoelectronic devices, covering a wide range of infrared wavelengths unattainable with In(Ga)As materials. Here, TRPL measurements were performed on molecular-beam epitaxy (MBE) grown GaAsSb/GaAs quantum dot structures: one with an InGaAs capping quantum well and one without. TRPL was used to determine the structures' ground state transition energies and their dependence on the number of photo-generated carriers.
The samples were excited using the PicoQuant pulsed laser diode emitting 780 nm, 60ps pulses with a repetition rate of 1MHz. Streak images were recorded with the Hamamatsu streak camera. In these type-II Ga(As)Sb QDs, the photoluminescence peak was seen to red-shift over time (Figs. 1 and 2). In combination with theoretical modelling, this was shown to be connected to Coulomb effects caused by the decreasing number of photo-generated carriers in the dots.