Summary
A new approach is used to measure ultrafast relaxation rates of photoexcited carriers in semiconductors. In contrast to time-resolved methods, one applies the exciting radiation much longer than the relaxation times involved to set up a new steady-state population equilibrium, which is probed by the absorption of a weak, tunable laser. The desired relaxation rate is obtained from the saturated-absorption spectrum. The optical-photon emission lifetime at hole energies of 0.15 eV inp-Ge is measured to be about 0.1 ps, in agreement with theory.
Riassunto
Si usa un nuovo metodo per misurare la velocità di rilassamento ultrarapido di portatori fotoeccitati in semiconduttori. In contrasto con i metodi di risoluzione in tempo, si applica una radiazione di eccitazione per un tempo maggiore del tempo di rilassamento coinvolto per ottenere un nuovo equilibrio di popolazione dello stato stazionario, che è messo in evidenza per mezzo di un fascio laser debole ed accordabile. La velocità desiderata del rilassamento è ottenuta dallo spettro di assorbimento saturato. La vita media di emissione del fonone ottico all’energie della buca di 0.15 eV inp-Ge è valutata essere circa 0.1ps, in accordo con la teoria.
Резюме
Используется новый подход для измерения ультрабыстрой релаксации фотовозбужденных носителей в полупроводниках. Из насыщенного спектра абсорбции получается искомая скорость релаксации. Измеряется время жизни оптического фонона при энергиях дырок 0.15 эВ вp-Ge. Время жизни составляет 0.1 пс, что согласуется с теоретическими предсказаниями.
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Footnotes
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Keilmann, F. Hot-hole relaxation inp-Ge investigated by saturation spectroscopy. Nuov Cim B 39, 666–670 (1977). https://doi.org/10.1007/BF02725809
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DOI: https://doi.org/10.1007/BF02725809