Abstract
We study the temperature dependence of time-resolved photoluminescence (PL) in closely packed alignment of Si nanodisks (NDs) with SiC barriers, fabricated by neutral beam etching using bio-nano-templates. The PL time profile indicates three decaying components with different decay times. The PL intensities in the two slower decaying components depend strongly on temperature. These temperature dependences of the PL intensity can be quantitatively explained by a three-level model with thermal activation energies of 410 and 490 meV, depending on the PL components. The activation energies explain PL quenching due to thermal escape of electrons from individual NDs. This thermal escape affects the PL decay times above 250 K. Dark states of photo-excited carriers originating from the separate localization of electron and hole into different NDs are elucidated with the localization energies of 70 and 90 meV. In contrast, the dynamics of the fastest PL decaying component is dominated by electron tunneling among NDs, where the PL intensity and decay time are constant for temperature.
Highlights
Attractive interdisciplinary research areas between electronic and photonic materials have been developed by modern semiconductor nanotechnology
We have recently proposed a fabrication process of Si nanodisk (ND) arrays, where the Si NDs are formed by damage-free neutral beam (NB) etching for Si thin films covered with etching masks of Fe nanoparticles which are regularly aligned by bio-protein engineering [15,16,17,18,19,20]
We have studied temperature dependences of timeresolved PL in the two-dimensional high-density Si ND arrays fabricated by NB etching using bio-nano-templates, where the PL time profiles with various temperatures are fitted by triple exponential decay curves
Summary
Attractive interdisciplinary research areas between electronic and photonic materials have been developed by modern semiconductor nanotechnology. We have recently proposed a fabrication process of Si nanodisk (ND) arrays, where the Si NDs are formed by damage-free neutral beam (NB) etching for Si thin films covered with etching masks of Fe nanoparticles which are regularly aligned by bio-protein engineering [15,16,17,18,19,20]. This fabrication process using the bio-templates enables us to prepare closely packed high-density Si NDs with the intentionally designed precise size and spacing in a nanometric scale with flexible film stacking. The PL quenching phenomena elucidated in this study will give us useful information about the dynamics of photo-excited carriers, such as carrier separation and transport, when we apply these Si NDs to solar cells and high-speed photonic devices
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