Near-field scanning optical microscopy with monolithic silicon light emitting diode on probe tip

Abstract

We describe optical and topographic imaging using a light emitting diode monolithically integrated on a silicon probe tip for near-field scanning optical microscopy (NSOM). The light emission resulted from a silicon dioxide layer buried between a phosphorus-doped N+ silicon layer and a gallium-doped P+ silicon region locally created at the tip by a focused ion beam. The tip was employed in a standard NSOM excitation setup. The probe successfully measured optical as well as topographic images of a chromium test pattern with imaging resolutions of 400 and 50nm, respectively. The directional resolution dependence of the acquired images directly corresponds to the shape, size, and polarity of the light source on the probe tip. To our knowledge, this report is the first successful near-field imaging result directly measured by such tip-embedded light sources.

Near-field scanning nanophotonic microscopy

“…With type-(1) and type-(2) probes, the light emission may not happen exactly at the physical tip of the scanning probe as indicated in Figure 1. We observed significant image shift between obtained topographic and optical images [4]. Because the type-(3) LED utilizes the probe tip as one of the electrodes, the location of the light source corresponds to the tip of the silicon probe.…”

“…This milling process induces re-deposition of gallium doped p-type silicon, which eventually creates a P-N junction [2] with a thin silicon dioxide layer as the light emitter [3]. The LED was typically driven at 4-8V and emitted light centered at 560nm [4]. (2) Electrostatic trapping of semiconductor nanoparticles Additional semiconductor nanoparticles at probe tip were used as the light source [5].…”

Scanning optical probe microscopy with submicrometer resolution using an organic photodetector

“…Davis et al 11 fabricated a Schottky photodiode having a very small ͑100 nm͒ optically sensitive region on a cantilever, and demonstrated optical imaging with a high resolution similar to the size of the diode aperture. Hoshino et al 12 demonstrated near-field imaging results using a monolithically grown silicon light emitting diode on a scanning probe tip. These probes do improve the SNR of typical NSOM and may be cost competitive with aperture and apertureless NSOM.…”

Cloaked Near-Field Scanning Optical Microscope Tip for Noninvasive Near-Field Imaging

“…Since we have proven that the cloak allows field penetration inside the cloak, at levels comparable to the uncloaked scenario, owing to reciprocity it is expected that a source placed inside the cloak may be able to efficiently radiate. In this sense, we have considered an active region at the NSOM tip, which may be obtained by coating the tip with a limited number of quantum dots or emitting molecules, as in a nano-LED for near-field illumination and sensing [4]. We consider an emitting molecule placed on the aperture of the same tip as in Fig.…”

“…In the aperture mode, the tip's opening is used to collect and/ or illuminate the subwavelength detail of objects of interest, whereas in the apertureless operation a very sharp tip is mainly used as a resonant scatterer to enhance and focus light on the subwavelength detail of interest. Recently, apertureless NSOMs have also been used in conjunction with collections of quantum dots localized on the tip to illuminate the detail of interest [4]. Although the apertureless method may ensure a smaller tip size and a larger scattering enhancement for small objects, which results in overall higher resolution, the aperture mode remains more popular, due to its flexibility and simplicity of operation, combined with longer history.…”