Visualization of the Local Carrier Dynamics in an InGaN Quantum Well Using Dual-Probe Scanning Near-Field Optical Microscopy

Abstract

We have developed dual-probe scanning near-field optical microscopy (SNOM) to visualize detailed carrier diffusion/recombination processes and applied it to the assessment of the local carrier dynamics in an InGaN single quantum well. It is clearly demonstrated that the carrier motion is strongly affected by the potential distribution within InGaN; potential ridges prevent carriers from diffusing outside them, whereas potential peaks cause carriers to travel a roundabout route around them. As a consequence, carriers anisotropically diffuse for several hundred nanometers along a specific direction toward a strong-photoluminescence domain. Thus, the dual-probe SNOM technique is a powerful nanoscopic tool, and may be versatile for characterizing photonic materials.

Development and Application of Multiple‐Probe Scanning Probe Microscopes

“…In fact, the MP-AFM has been used for characterizing photonic materials using a scanning near-fi eld optical microscopy technique. [ 85 ] Furthermore, the MP-AFM can be expected to be used not only for electrical measurements but also for the manipulation of samples especially in the biological fi eld. [ 44 ] Since the MP-AFM can be utilized at any desired position regardless of the conductivity of the substrate without using an SEM, it provides a new approach to probing local signal transfers in a wide range of materials in various environments, such as in vacuum, in air and in a liquid.…”

Polarization-Resolved Near-Field Spectroscopy of Localized States in m -Plane InxGa1−xIvanov1, Marcinkevičius2, Mensi3 et al. 2017Phys. Rev. Applied160100View full textAdd to dashboardCite

“…For In x Ga 1−x N QWs with large band potential fluctuations, the diffusion length is approximately 100 nm [13]. The near-field PL measurement data are complemented by standard time-integrated far-field PL measured with the same excitation and detection equipment in the 4-300 K temperature range.…”

“…Properties of localized states have been studied in QWs of nonpolar and semipolar crystallographic orientations, and correlations between the surface morphology and properties of photoluminescence (PL) parameters have been established [7][8][9][10]. SNOM has also enabled studies of carrier transport on a 100-nm scale [13]. However, within the large body of SNOM research, a parameter that has been largely overlooked is the polarization of the emitted radiation.…”

Spatially Resolved Spectroscopy of Blue and Green InGaN Quantum Wells by Scanning Near‐Field Optical Microscopy

“…The relationship between potential barriers formed at threading dislocations and IQE in InGaN multiple quantum wells (MQWs) has been investigated by several groups. Excitation power‐dependent and time‐resolved SNOM‐PL has shown that the potential barriers improve the IQE in blue QWs but not in green QWs . High‐energy emissions corresponding to potential barriers were also confirmed in InGaN QW structures and LEDs emitting in the blue to green spectral regions, and the relationship with the V‐pit size was systematically investigated by PL .…”

“…Excitation power-dependent and timeresolved SNOM-PL has shown that the potential barriers improve the IQE in blue QWs but not in green QWs. [7][8][9] High-energy emissions corresponding to potential barriers were also confirmed in InGaN QW structures and LEDs emitting in the blue to green spectral regions, and the relationship with the V-pit size was systematically investigated by PL. [10][11][12] Increasing the V-pit size by introducing super lattices (SLs) before forming MQWs tends to increase the IQE.…”