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Picosecond Relaxation Processes of High Density Electron–Hole Plasma in CdSe
Author(s) -
Yoshida H.,
Saito H.,
Shionoya S.
Publication year - 1981
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221040136
Subject(s) - picosecond , excitation , atomic physics , plasma , photon energy , auger effect , electron , materials science , relaxation (psychology) , electron temperature , auger , chemistry , photon , optics , physics , laser , quantum mechanics , psychology , social psychology
Picosecond time‐resolved spectra of the spontaneous luminescence from high density electron‐hole plasma in CdSe are measured at 4.2 K with changing excitation photon energy in the vicinity of the bandgap energy by using tunable picosecond pulses. Spectra observed are analyzed, and the electron‐hole concentration and effective carrier temperature of the plasma are obtained as a function of excitation photon energy as well as of the delay time. It is found that both the electron‐hole concentration and effective carrier temperature decrease remarkably for the first 150 ps after pulse excitation, and that thereafter the concentration and temperature remain almost unchanged at ≈3 × 10 17 cm −3 and ≈20 K, respectively, until to the very late stage down to the 800 ps delay time. It is concluded that the effective carrier temperature does not fall below ≈20 K in spite of decreasing the excess energy given to the carriers at the instance of pulse excitation by means of changing the excitation photon energy. It is sure that there exists a process which makes the plasma hot. The phonon‐assisted Auger process is suggested as such a process.