Leszek Bychto

Photoacoustic studies of Zn1-xBexSe mixed crystals: two-layer approach

Abstract Using the photoacoustic spectroscopy, the following composition-dependent material parameters of Zn 1− x Be x Se mixed crystals were determined: thermal diffusivity, optical absorption coefficient spectra in the region of high absorption and in the Urbachs edge region, the energy gap values and the thermal and compositional broadening of the absorption bands. The quality of the surface of the samples and its influence on the determination of these parameters was checked and discussed.

Experimental investigations of the dependence of the lifetime of the optically generated minority carriers in n-type silicon on the intensity of its illumination

This paper presents experimental and theoretical dependences of the lifetime of minority carriers in n-type silicon on the intensity of its illumination. The experimental characteristics have been interpreted theoretically in the frame of Shockley Read Hall (SRH) statistics. The lifetimes of minority carriers for a low intensity of illumination were measured with the Surface Photovoltage (SPV) method while for the high intensity a Modulated Free Carrier Absorption (MFCA) method was applied. The obtained results clearly show that the experimentally obtained lifetimes of carriers can be compared only for the same conditions of illumination of the sample. Streszczenie. Praca przedstawia doświadczalne i teoretyczne zależności czasu życia nośników mniejszościowych w krzemie typu n od natężenia światła. Charakterystyki doświadczalne zostały zinterpretowane teoretycznie w modelu Shockley Read Hall (SRH). Czasy życia nośników dla małych natężeń światła oświetlajacch próbkębyły mierzone metodą SPV podczas gdy dla dużych natężeń światła wykorzystano metodę Modulacji Absorpcji Światła na Swobodnych Nośnikach (MFCA). Uzyskane rezutaty jasno pokazują, że czasy życia uzyskane eksperymentalnie mogą być porównywane tylko dla tych samych warunków oświetlanie próbek. (Badania eksperymentalne zależności czasu życia optycznie generowanych nośników mniejszościowych w krzemie typu n od natężenia światła).

Influence of light intensity on the lifetime of carriers in silicon investigated by a photoacoustic method

Abstract The paper presents experimental results of the lifetime of light induced excess carriers in the n−type silicon. The lifetimes of carriers of silicon crystals were analysed as a function of the intensity of light illuminating the sample. As a measurement method of the lifetime of carriers, the photoacoustic method in a transmission configuration with different surfaces was used. The dependence character was next analysed in the frame of the Shockley Reed Hall statistics in approximation of the light low intensity.

Determination of the Optical Absorption Coefficient of Zn1-x-yBexMgySe Mixed Crystals from the PAS Experiments-Improved Approach

In this paper the results of the photoacoustic spectroscopic experiments performed on Zn 1-x-y Be x Mg y Se mixed crystals are presented. In the course of the study the PA spectra of the amplitude and phase of the PA signals were measured at different frequencies of modulation. The measurements were performed for the series of samples at x=0.14 y=0.06 after different technological treatment e.g. as grown, annealed, polished and unpolished samples. From the measurements were determined: energy gap value, optical absorption coefficient, Urbach edge contribution, contribution of the surface signal to the total PA signal. The influence of the technological treatment of the samples on the above parameters was determined and the results were discussed in one layer and two layers models.

Determination of the quality of the soldering of semiconductor chips by the alternating-heat-flux method

The results of the photoacoustic measurements of the semiconductor chips of the bipolar transistors soldered to the lead frame are presented. The correlation between the phase of the temperature and the force necessary for the detachment of the chips from the lead frames was observed.