Transparent Wafer Research Articles

Observation of silicon wafer emissivity in rapid thermal processing chambers for pyrometric temperature monitoring

The emissivity of silicon wafers in a rapid thermal processing chamber has been measured as a function of the wafer temperature. Wafers with different surface roughness and layers have been studied. For transparent wafers, both sides of the wafer affect the emissivity. This emissivity is not only affected by surface roughness, but also by the layers deposited on the wafer. It has also been observed that while the emissivity increases rapidly as the temperature increases from its room value to 600 °C, the emissivity decreases with a slope of −8.89×10−5 °C−1 for temperatures larger than 600 °C.

Polarized IR Spectra of Decacarbonyldimanganese(O) and Decacarbonyldirhenium(O) Oriented in Stretched Polyethylene Films

Polarized IR spectroscopy can provide useful information about the orientation of molecules in the solid state and is particularly important in substantiating vibrational assignments. To do these measurements, it is necessary to cut thin, transparent wafers from single crystals of the material of interest—not always a trivial task. An alternative approach is to orient the compound in a nematic liquid crystal solvent, a procedure that has been successfully used in studying the polarized IR spectra of transition metal carbonyl complexes such as M2(CO)10 (M = Mn, Re), (η5-C5H5) Mn (CO)3, and Cr(CO)6. Liquid crystal solvents are somewhat limited in their use, however, chiefly because of the complexity of their IR spectra, but their expense and their somewhat restricted shelf-lives are also important factors. We present here a novel alternative method of obtaining polarized IR spectra.

High-efficiency GaAs0.7P0.3 solar cell on a transparent GaP wafer

The fabrication of a high performance GaAs0.7P0.3 solar cell on a transparent GaP substrate with an AM1.5 efficiency of 15.4% for a concentration ratio of 30× is reported for the first time. The measured transparency of the GaP substrate allows these cells to be mechanically stacked on silicon solar cells in a manner that should yield combined conversion efficiencies well over 25%. This mechanically stacked two-band-gap cell design is particularly attractive because it utilizes the already well-developed Si solar cell and because the materials foundation for the GaAs0.7P0.3 on GaP cell has been laid by work on light emitting diodes.