Search Results (2 total)

The polarized directional spectral (3 μm≤λ≤14 μm) emittances (PDSE’s) of highly doped, micromachined, periodic structures on silicon were measured. These structures have dimensions that are comparable to the wavelengths of the measured radiation. Significant anisotropies and maxima were found for the s and p PDSE’s measured in emittance planes parallel and perpendicular to the grating-repeat vector. Wood’s singularities were clearly visible in the p PDSE on shallow gratings (depth ≤1.5 μm). Periodic maxima were observed in both the s and p PDSE in the emittance plane perpendicular to the grating vector due to standing-wave modes in the slots of the grating. It is concluded that the PDSE provides detailed information on the characteristics of the electromagnetic modes associated with surface microstructures.

The normal, polarized spectral (3 μm≤λ≤14 μm) emittances of highly doped, micromachined, periodic structures on heavily phosphorus-doped (110) silicon ([P]∼5×10¹⁹ cm^-3) were measured for pattern repeat scales, Λ, of 10, 14, 18, and 22 μm and depths ranging from 0.7 to 45 μm. These structures have dimensions that are comparable to the wavelengths of the measured radiation. The s-polarization vector in these measurements was perpendicular to the grating vector. The data demonstrated that the emittance from the deep structures is dominated by standing (quantized) electromagnetic waves in a direction normal to the surface similar to those in an organ pipe. Wood’s singularities were clearly visible in the p-polarized emission on shallow gratings (depth ≤1.5 μm). It is concluded that these measurements, particularly the s-polarized emission from deep gratings, cannot be explained by calculations of electromagnetic singularities on lamellar gratings.