Time-Resolved Photoluminescence

Aim

This technique is used to measure the excess carrier lifetime (hole or electron) in direct bandgap semiconducteur (II-V or II-VI). This parameter is usefull for heterojunctions, bipolar transistors, LED, LASER or photovoltaic systems.

Experiment

The semicondutor sample is excited by a pulsed light source (Titan : saphir laser) with an energy lower than the sample bandgap. The photoluminescence decay is spectrally dispersed using a monochromator and detected with a streak camera.

Results

The streak camera gives the decay curve of the semiconductor photoluminescence. This curve is fitted to an exponential based model. If the semiconductor is doped (or undoped), the carrier lifetime will be the decay time (or respectivelly the double of this time).

Order of magnitude

Carrier Lifetime :      5ps - 200ns

SC bandgap :           0.8eV - 5eV

0.25µm - 1.55µm