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Pattern distortion caused by resist heating is believed to contribute significantly to errors in feature size and pattern placement. A number of models have been proposed to predict the temperature rise of resist heating but experimental results are scarce. We fabricated and calibrated thin film gold/nickel thermocouples with (400 nm)2 junction size and used these to measure work-piece heating during electron-beam exposure. Irradiation by a 15 kV electron beam of 600 nA and 2 μm radius caused a temperature rise of 70 K, about 15% lower than the calculated result. The discrepancy may be due to the differences between the energy deposition profiles used in modeling and those prevailing in the experiments.

The frequency dependence of the external quantum efficiency (EQE) of high-quality multijunction solar cells was examined by the modulated photocurrent spectroscopy method via an optical setup comprised of a light-pipe-coupled compact LED array. The optical excitation was achieved through sinusoidal electrical modulation of an appropriate LED by a custom-designed, high bandwidth amplifier. We observed unique features in the amplitude and phase data of the EQE frequency sweeps that are very sensitive to various subcell parameters and light bias conditions. These features are discussed extensively within the context of an AC equivalent circuit model, showing remarkable agreement between the experimental data and the proposed model.

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