Photoexcited carrier and phonon morphology of InSb observed with an ultrafast pump-probe microscope

Abstract

The ultrafast pump-probe microscope has been utilized to spatially map the ultrafast dynamics of photoexcited carriers and phonons in InSb with varied carrier concentrations. In this study, the negative and positive components of transient reflectivity-change spectra (ΔR/R) are associated with the dynamics of photoexcited holes and phonons, respectively. The mapping of phonon morphology (i.e. positive ΔR/R on a ps-ns timescale) shows the delocalized electron-phonon coupling in InSb, especially for large carrier concentrations. In contrast, the recombination of electrons and holes is rather localized inside the pumped spot. According to morphological analyses of oscillatory signals in ΔR/R, we found that an electric field applied to InSb can further manipulate the phonon strength and lifetime. For the case of large carrier concentrations, the spatial breadth of phonons has been first observed in InSb.

Multi-technique characterisation of InAs-on-GaAs wafers with circular defect pattern

“…For A III B V semiconductor compounds, especially 6.1 Å-family materials, there has also been great progress in uniformity improvements and mapping techniques developments. Many recent research studies on thick layers of arsenides (e.g., InAs, GaAs), antimonides (e.g., InSb, GaSb), and their ternary alloys (e.g., InAs1-xSbx) [20][21][22][23], as well as low-dimensional structures composed of aforementioned compositions, like quantum dots (QDs) [24][25][26], nanowires [27,28], quantum-well infrared photodetectors (QWIPs) [29], or type-II superlattices (T2SLs) [30][31][32], indicate strong interest in the topic. Considering mapping, the aim is to obtain as much information as possible using non-destructive techniques.…”

“…Considering mapping, the aim is to obtain as much information as possible using non-destructive techniques. For this reason, the optical or semi-optical methods such as: high-resolution X-ray diffraction (HR-XRD) [24], photoluminescence (PL) [22,24,25,30,31,33], local photocurrent mapping (LPM) [32,34], spatially separated pump-probe (SSPP) spectra [21], lock-in thermography [20], scanning thermal microscopy (STM) [28] are mostly preferred. In many cases, however, contactless electric [35] or non-destructive tactile methods such as atomic force microscopy (AFM) [23] are also used.…”