Growth and optical characterisation of multilayers of InGaN quantum dots

Morphological, structural, and emission characterization of trench defects in InGaN/GaN quantum well structures

“…10 Trimethylgallium (TMG), trimethylindium (TMI), and ammonia (NH 3 ) were used as precursors with N 2 as the carrier gas for InGaN growth. We have observed trench defects in a wide range of samples, with a variety of different QW and barrier conditions, and even in quantum dot samples, 11 suggesting that they are a very common phenomenon and not the product of a specific growth technique. The density of trench defects in these samples ranges from 1 Â 10 7 cm À2 to 5 Â 10 8 cm À2 .…”

Bias dependence and correlation of the cathodoluminescence and electron beam induced current from an InGaN/GaN light emitting diode

“…CL hyperspectral imaging-the recording of a full spectrum at each pixel in a scan-has proven to be of significant use in mapping and correlating variations in the spectral emission parameters of epilayers, 2,3 multiquantum well (MQW) heterostructures, 4 and optoelectronic nanostructures. [5][6][7] However, luminescence is just one of the many consequences of the interaction of the electron beam with the material. If the device under excitation is connected to a closed circuit, a portion of the generated charge carriers can escape the material and be measured as the electron beam induced current (EBIC), provided there is a driving force in the circuit.…”

Spectral diffusion time scales in InGaN/GaN quantum dots

“…In this work, we report excitation dependent measurements of the long-term (occurring on time scales of seconds) and fast temporal scale ($nanosecond) spectral diffusion phenomena in an isolated self-assembled InGaN/GaN QD. The QDs were grown on c-plane GaN/sapphire pseudo-substrates using a modified droplet epitaxy method [32][33][34] by Metal Organic Chemical Vapour Deposition on a 6 Â 2 in. Thomas Swan close-coupled showerhead reactor and are situated in an etched micro-pillar structure containing porous DBRs (formed by electrochemical etching) for enhanced emission extraction efficiency.…”

“…Indeed, we estimate that for every optically active QD there may be up to a few tens of non-optically active structures. 27,34 While measuring such spectral diffusion on these large time scales is important to understand the dynamics that play a role in the emission properties of the dots, it is actually the environmental fluctuations that occur on the fastest time scale that are the most important. This is because it is the fastest time scale of the spectral jumps that will determine how many photons can be generated before the emission energy shifts.…”