Dynamics of non‐equilibrium charge carriers in p‐germanium doped by gallium

• Published in: physica status solidi (b) 2017-06, Vol.254 (6), p.n/a
• Main Authors: Deßmann, Nils, Pavlov, S. G., Tsyplenkov, V. V., Orlova, E. E., Pohl, A., Shastin, V. N., Zhukavin, R. Kh, Winnerl, S., Mittendorff, M., Klopf, J. M., Abrosimov, N. V., Schneider, H., Hübers, H.‐W.
• Format: Article
• Language: English
• Subjects: acceptor states; electronic capture; free electron laser; germanium; pump–probe experiment
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201600803

The low‐temperature capture processes of non‐equilibrium holes into gallium acceptors in moderately doped p‐germanium (NA ≈ 2 × 1015 cm−3) has been investigated by a single‐color pump–probe experiment using the free electron laser FELBE. The capture time decreases with increasing average photon flux density of the excitation pulse from about 10.9 ns (at ∼1.2 × 1024 cm−2 s−1) to ∼1.2 ns (∼2 × 1026 cm−2 s−1). Relaxation inside the valence band is almost independent on pump light intensity and its characteristic time is about 200 ps. In Addition, the intracenter relaxation times of the lowest excited Ga states were measured. The lifetimes scale with the phonon density of states controlling the bound hole − acoustic phonon interaction. The lifetime of the lowest excited state, 1Γ8−, was measured to be ∼275 ps; while the lifetimes of the higher excited states, 2Γ8− and 3Γ8−, were found to be ∼160 ps.