Near-field scanning optical microscopic transient lens for carrier dynamics study in InGaN∕GaN

Abstract

Time-resolved microscopic transient lens ͑TR-M-TL͒ and near-field scanning optical microscopic transient lens ͑NSOM-TL͒ were performed to reveal temporal and spatial behavior of carrier dynamics in InGaN/ GaN quantum wells. The carrier and thermal dynamics were observed through the time profile of the TR-M-TL signal. Also, NSOM-photoluminescence and NSOM-TL images were observed at the same time. By comparing these two images, both radiative and nonradiative recombination centers in InGaN active layer were unambiguously discriminated with submicrometer scale. Such nonradiative carrier dynamics has been difficult to observe by conventional techniques in spite of its importance.

Carrier localization in m-plane InGaN/GaN quantum wells probed by scanning near field optical spectroscopy

“…Electroluminescence and photoluminescence ͑PL͒ SNOM studies of c-plane InGaN QWs have identified carrier localization and nonradiative recombination centers, [7][8][9] and revealed potential barriers around the extended defects. Scanning near field optical microscopy ͑SNOM͒, which provides subwavelength spatial resolution, is a more powerful technique for characterizing the carrier localization.…”

An efficiency droop model of the saturated radiative recombination rate and its verification by radiative and nonradiative carrier lifetime measurements in InGaN-based light emitting diodes

“…The lateral sizes of In-rich area are reported in a wide range from a few nm to hundreds of nm and they form a sort of Inrich quantum disks (Q-disks) or quantum dots (Q-dots) [13,14]. The volume of Q-disks (or Q-dots) are much smaller than the physical volume of a QW, namely V eff << V a .…”

“…Lots of experimental evidences have suggested the existence of In-rich areas in the active layer of the InGaN-based blue LED, which can act as localization centers of carriers and behave more like quantum disks (Q-disks) or quantum dots (Q-dots) with reduced density of states [13][14]. The existence of In-rich areas implies that the effective active volume is smaller than the nominal volume of QWs.…”

Fabrication of a plasmonic nanocone on top of an AFM cantilever

“…NSOM is not only used to optically study the surface morphology, but has been successfully integrated with different spectroscopy techniques such as Raman (TERS) [3,4], photoluminescence [5], time resolved measurements [6], etc. It has been used to study a variety of materials, such as solid state quantum nanostructures [7,8], single molecules [9] or soft biological tissues [10,11].…”