We demonstrate that mid-infrared surface phonon polariton propagation on a SiC crystal can be imaged by scattering-type near-field optical microscopy. From the infrared images, we measure the wave vector and the propagation length of locally excited surface phonon polaritons. Our method can be also applied to surface plasmon polaritons and allows to study surface polaritons in subwavelength-scale structures.

Nanostructures are at the heart of ever-shrinking electronic and photonic devices. The engineering of nanocomposite materials, building blocks, [1,2] and conduction properties [3,4] necessitate advanced microscopy tools to assess critical dimensional, compositional, structural, and conduction properties for analysis and quality control. [5] Here we demonstrate with industrial bipolar and metal-oxide-semiconductor (MOS) devices that mid-IR scattering-type near-field optical microscopy (s-SNOM) [6,7] has the potential to probe all of these parameters, and thereby excels electron and other scanning-probe microscopies. . We image cross sections of the devices routinely prepared for failure analysis at 30 nm resolution, and this limit could be pushed below 10 nm in the course of future development. Resolution combined with high specificity to material and conductivity properties makes IR s-SNOM a promising tool beyond the microelectronics field for chemical nanotechnology, molecular electronics, photonics, and bioanalytics.IR spectroscopy has tremendous merit in the chemical and structural analyses of materials and in conduction assessment, but until now the limited spatial resolution has prevented its application in industrial failure analysis and quality control. Instead, scanning electron microscopy (SEM) is employed, which offers nanoscale resolution and sensitivity to materials, particularly when combined with Auger, energy-dispersive X-ray (EDX), or wavelength-dispersive X-ray (WDX) spectroscopies. However, only qualitative doping information with decoration-etched samples can be obtained. Transmission electron microscopy (TEM) offers elemental sensitivity [8,9] in combination with EDX or electron energy loss spectroscopy (EELS), but it suffers from complicated and time-consuming sample preparation. Moreover, the feature sizes of semiconductor structures have already been reduced below the minimum thickness of TEM samples so that details can no longer be imaged.[10] Scanning probe microscopy (SPM) provides topography, and in the extended versions of scanning capacitance microscopy (SCM) [11] and scanning spreading resistance microscopy (SSRM), also doping [12] but poor material sensitivity. We introduce IR s-SNOM as a method of choice, as SNOM generally extends SPM by the optical near-field interaction between tip and sample, and it thus enables the power of optical spectroscopies, such as fluorescence, [13] Raman, [14,15] or IR, [6,[16][17][18][19][20][21][22][23] to be exploited with nanoscale spatial resolution.In particular, IR s-SNOM has a demonstrated specificity to chemical composition, [22,24] material category, [7] structural variation, [25,26] and electrical conduction. [17,27,28] Our IR s-SNOM technique is based on atomic force microscopy (AFM) as described previously; [6,29] imaging relies on a commercial, Pt-coated, cantilevered tip operating in tapping mode (frequency X ≈ 30 kHz) with a 20-30 nm radius of curvature. The tip is illuminated by a focused CO 2 laser beam at a wavelength k = 10.7 lm. Th...

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The luminescence of GaAs quantum-well-based microstructures was investigated with a scanning near-field optical microscope at different ambient temperatures. The scanning tip was fabricated from an optical fiber. The excitation laser beam (514 nm, 100–300 mW) was focused onto the opposite end of the fiber. The carrier distribution in the sample was investigated using the high-energy tail of the luminescence peak. Temperature fits show no overheating of the sample despite the expected high temperatures of the tip.

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Articles you may be interested inApplication of triangular atomic force microscopy cantilevers to friction measurement with the improved parallel scan method Rev. Sci. Instrum. 80, 023704 (2009); 10.1063/1.3079685Demonstration of low-temperature atomic force microscope with atomic resolution using piezoresistive cantilevers Rev.The frequency response of an atomic force microscope silicon cantilever located in a vacuum cryostat chamber was investigated. The resonance frequency and the peak width were extracted by a Lorentzian fit of the resonance curves for different sample temperatures ͑15-310 K͒. Frequency shifts significantly less than one could expect from known temperature dependencies of Young's modulus and the density of silicon were found. The estimations described in this article show that the temperature of a silicon cantilever is mainly defined by the temperature of its holder, mainly due to the thermal conductivity of silicon. Thermal radiation emission plays a minor role in cooling the cantilever. Furthermore, heat transport through tip-sample contact, as well as contact with the environmental gas, could be neglected.