Carrier lifetime characterization in solar cell and light emitting diode materials by time-resolved photoluminescence and differential transmission is of high importance, indicating cost-efficient streak camera suitable for such tests would be highly demanded. In this work an electro-optic deflecting device is extended to full functionality streak camera operating in wide spectral range (200-2000 nm) by using electro-optic DKDP crystals. Setup, consisting of picosecond laser for sample excitation, electro-optic deflector and imaging spectrograph with silicon and InGaAs cameras, allows spectral and temporal imaging of recombination dynamics in semiconductor materials, with variable bandgap and composition (tested on metal-halide perovskite crystal), achieving temporal resolution up to 50 ps. For the case of time-resolved differential transmission, broadband <50 ps pulsed or CW xenon light source can be used for absorption change probing.
Time-resolved photoluminescence and light-induced transient grating techniques were applied for the comparative investigation of the evolution of the internal quantum efficiency and of the carrier diffusion in AlxGa1-xN (x > 0.6) heterostructures in 80 – 550 K temperature range and for excitations from 1 µJcm-2 to 1 mJcm-2. The decrease of the photoluminescence efficiency measured at high excitations and temperatures is quantitatively correlated to the increase of the diffusion coefficients of carriers and to the increase of their non-radiative recombination rate on vacancies. Complex numerical modelling provides a full set of carrier and exciton recombination parameters.
Optically-injected carrier dynamics were investigated in bulk polar and nonpolar GaN in 1015-to-1020 cm-3 carrier
density range, exploring single- and two-photon photoexcitation conditions. The excitation decay and recombination
rates were monitored by time-resolved photoluminescence and free-carrier absorption techniques, while diffusivity
was investigated by light-diffraction on transient grating technique. Carrier dynamics in c- and m-plane thick
freestanding HVPE GaN revealed nearly linear increase of carrier lifetime with temperature in the 80 - 800 K range
whereas the bipolar carrier diffusivity decreased with temperature. This feature suggests that the measured long
lifetime values of 40-50 ns at RT result from diffusion-governed carrier flow to interface defects at GaN hexagons,
which act as centers of nonradiative recombination. The fast PL transients under carrier injection to submicrometer
thick layer were fitted by using the determined diffusivity and lifetime values and revealed a strong impact of
vertical carrier diffusion, surface recombination, and reabsorption processes. Radiative and nonradiative emission
rates were analyzed by various optical techniques to discriminate contribution of excitons and free carriers at various
temperatures and injected carrier densities.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.