S. Heisig

Scanning near-field optical microscopy in the near-infrared region using light emitting cantilever probes

We present an application of an active emitting cantilever probe for scanning near-field optical microscopy and scanning force microscopy. A vertical cavity surface emitting laser (VCSEL) integrated in a galliumarsenide (GaAs) cantilever serves as a light source at 980 nm emission wavelength that is below the band gap energy of the GaAs substrate material. The VCSEL of 8 μm diameter is centered with respect to the metalized GaAs tip and illuminates a small near-field aperture at its apex. Aperture fabrication is accomplished by a proper thermal metal evaporation process. Optical measurements on a Fischer projection pattern revealed an edge resolution of about 80 nm.

Optical active gallium arsenide cantilever probes for combined scanning near-field optical microscopy and scanning force microscopy

The fabrication process of a GaAs cantilever probe with an integrated vertical cavity surface emitting laser (VCSEL) for scanning near-field optical microscopy applications is described. The VCSEL illuminates an aperture in a thin Au/Ge metallization layer at the tip apex. The light emitting aperture serves as a subwavelength light source and thus can be used to reduce the lateral resolution in transmission imaging beyond the far-field diffraction limit. The light beam of the VCSEL emitted to the opposite side is exploited for the detection of the mechanical deflection of the cantilever that additionally facilitates the scanning force microscopy setup.

Optical Active Gallium Arsenide Probes for Scanning Probe Microscopy

In order to produce microelectromechanical systems on base of gallium arsenide it is necessary to develop novel etching techniques. The conventional dip etching is not suitable to fabricate such systems reliably and with sufficiently small thickness variations. To overcome this problem we used a modified spray etching technique. A comparison between both methods is given.

Cantilever probes for spatio-temporal imaging of voltage pulses with an ultrafast scanning probe microscope

We report on a novel cantilever probe for the investigation of ultrafast signals. High temporal resolution is achieved by integrating a photoconductive switch within a coplanar waveguide structure onto a low temperature GaAs coated GaAs cantilever. Experimental results and numerical calculations on the detection of picosecond electrical signals based on the optoelectronic technique of photoconductive sampling are presented.

Application and characterization of combined SNOM/SFM cantilever probes

A combined SNOM/SFM aperture probe is presented which is based on a conventional scanning force microscopy cantilever. Probe fabrication was performed in a batch process which allows to get reproducible mechanical and optical properties. For SNOM applications a tip is integrated at the very end of the cantilever which consists of a hollow metal pyramid with a miniaturized aperture of about 60 nm. To select the appropriate tip material the transmissivity of different metals were investigated in the visible range. The SNOM/SFM probes were characterized both mechanically and optically, e.g. the transmission of apertures is measured as a function of their size. To determined the lateral resolution in the optical transmission mode measurements on test samples are shown. Additionally, a novel probe design is introduced where the geometry of the single aperture tip is altered to obtain a double aperture tip.