Excellent surface passivation of crystalline silicon wafers is known to occur following post-deposition thermal annealing of intrinsic a-Si:H thin-film layers deposited by plasma-enhanced chemical vapor deposition. In this work, layer thicknesses ranging from 5 to 50 nm were used to indirectly study the surface passivation mechanism by sequentially measuring the effective carrier lifetime as a function of annealing time and temperature. From this, an activation energy of 0.7±0.1 eV was calculated, suggesting that surface passivation is reaction-limited and not determined by a bulk hydrogen diffusion process. We conclude that the primary surface reaction stems from surface rearrangement of hydrogen already near the interface.

Using laser terahertz emission microscopy, we measured laser-excited terahertz (THz) emission from silicon wafers with silicon-oxide passivation layers, revealing a strong correlation between the THz waveform and the surface potential. The surface potential was electrically tuned by a semitransparent top electrode disc and evaluated by measuring capacitance–voltage characteristics. The waveform changed with external bias and inverted near the flatband voltage, and changes appeared in the peak amplitude were similar to the capacitance–voltage characteristics. These results indicate that by analyzing the waveform of laser-excited THz emission generated by laser terahertz emission microscopy, we could quantitatively measure and map the internal field of surface band bending in semiconductors.

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We report high-resolution saturated-absorption spectra recorded by use of a few microwatts of radiation generated in a single pass by difference-frequency mixing. These results were obtained without the use of buildup cavities for the nonlinear mixing or for the saturation spectroscopy. We show high-quality saturated-absorption signals for the fundamental rovibrational band of CO(2) near 4.3 mum. Convenient sources and frequency-conversion devices open new possibilities for sub-Doppler spectroscopy in the infrared.

In this work, we propose and demonstrate a durable and distributable Lambertian light-emitter secondary standard using the electroluminescence (EL) of a Si solar cell. This standard is useful for calibration of the absolute sensitivity of an EL-imaging infrared camera used to acquire quick on-site measurements of the absolute EL efficiencies of individual Si solar cells in modules and arrays. The developed method enables the realization of quantitative open-circuit voltage mapping.