PL Spatial Variation in InGaN/GaN MQWs Studied by Confocal Microscopy and TRPL Spectroscopy

Abstract

Confocal laser scanning microscopy and time-resolved photoluminescence (TRPL) spectroscopy were used to study blue-emitting InGaN/GaN multiple quantum wells. Spatial and spectral variations of photoluminescence (PL) were observed over submicron-scale regions. Spectral measurements showed that the bright regions have a higher PL intensity as well as smaller peak energy than the dark regions. Correlations among the bright region-dark region PL peak energy difference, the average PL intensity, the PL FWHM, the bright region PL intensity, and the extent of PL intensity fluctuation were observed. As the energy difference increased, the average PL intensity, the PL FWHM, and the bright region PL intensity increased, with a higher degree of areal PL intensity fluctuations. TRPL measurements and calculations showed that the effective PL lifetime at bright regions was longer than that at dark regions, and bright region lifetime increases as energy difference increases, possibly as a result of stronger confinement.

High-Resolution Dynamic Pressure Sensor Array Based on Piezo-phototronic Effect Tuned Photoluminescence Imaging

“…Meanwhile, the noncompressed nanopillars had no piezoelectric-induced charges, thus no change of PL intensity could be found from these nanopillars. In addition, it is noted that the PL dynamic process takes place at a very short time of nanoseconds or less, , which is beneficial for fast-speed optical imaging. By using a charge-coupled device (CCD) to collect and monitor the PL intensity of all sensors, the all-optical imaging of the applied pressure distribution can readily be attained.…”

“…The vertically dynamic response of pressure sensing corresponds to the real-time image changes of the patterned BINN stamp. Due to the ultrafast PL recombination process in nanoseconds or less, , it demonstrates unprecedented fast response for dynamic pressure/strain sensing, providing and guaranteeing very good time resolution of mechanical motions. Also, after 1000 pressing/releasing cycles, no degradation occurs in the pressure-sensitive PL imaging, exhibiting a good reliability and mechanical robustness of our array device, as shown in Figure S2.…”

(Invited) Study of Carrier Localization, Carrier Transportation and Carrier Recombination Processes in Blue-Emitting InGaN/GaN MQWs

“…This excitation condition was low enough to avoid sample heating. Details of the CLSM and TRPL system are described elsewhere (6).…”

Uncovering the carrier dynamics of AlInGaN semiconductors using time-resolved cathodoluminescence

“…To investigate the carrier dynamics of semiconducting materials, optical excitation based techniques such as scanning near-field optical microscopy (SNOM) and time-resolved photoluminescence (TRPL) can be utilised [28][29][30][31]. Some of these techniques, such as SNOM, can overcome the diffraction limit and achieve a nanometre spatial resolution allowing the spatial variation of carrier dynamics to be studied [29].…”