Relaxation of the Excited States of Arsenic in Strained Germanium
- PDF / 970,354 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 40 Downloads / 194 Views
INTERNATIONAL SYMPOSIUM “NANOPHYSICS AND NANOELECTRONICS”, NIZHNY NOVGOROD, MARCH 10–13, 2020
Relaxation of the Excited States of Arsenic in Strained Germanium K. A. Kovalevskya,*, Yu. Yu. Choporovab,c, R. Kh. Zhukavina, N. V. Abrosimovd, S. G. Pavlove, H.-W. Hüberse,f, V. V. Tsyplenkova, V. D. Kukotenkob,c, B. A. Knyazevb,c, and V. N. Shastina a Institute
b
for Physics of Microstructures, Russian Academy of Sciences, Nizhny Novgorod, 603950 Russia Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia c Novosibirsk State University, Novosibirsk, 630090 Russia d Leibniz Institute of Crystal Growth, Berlin, 12489 Germany e Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berlin, 12489 Germany f Institute für Physik, Humboldt-Universität zu Berlin, Berlin, 12489 Germany *e-mail: [email protected] Received April 15, 2020; revised April 21, 2020; accepted April 21, 2020
Abstract—The relaxation times of the lower p states of the arsenic donor in a germanium crystal strained along the [111] crystallographic direction are studied. Measurements are performed by the pump–probe method, using free-electron laser radiation. The states are excited from the 1s (Γ1) ground state. The experimentally measured decay times of the 2p0, 3p0, and 2p± states are 1.3, no more than 0.2, and 0.4 ns, respectively. It is shown that the relatively high relaxation rate of the 2p± state is defined by the interaction with intravalley TA photons. Keywords: germanium, arsenic, uniaxial strain, pump–probe method, intracenter optical excitation, phonons DOI: 10.1134/S1063782620100188
1. INTRODUCTION In recent years, a new wave of interest in the properties of shallow impurities in semiconductors [1], specifically, in studies of the relaxation of excited states has been created in the context of the appearance of new problems of quantum radiophysics [2] and quantum computations [3], as well as new experimental possibilities of directly analyzing the ultrafast and, at the same time, spectrally resolved dynamics of nonequilibrium charge carriers [4]. The first experimental data on the relaxation times of donors and acceptors in unstrained germanium were obtained as early as the 1970s, using room-temperature thermal radiation as an excitation source, whilst the probe radiation was the emission from a backward-wave tube [5]. Later on, with the use of an optical shutter to reduce the duration of the free-electron laser (FEL) radiation pulse to nanoseconds, it was found that the photoresponse time of p-Ge with the acceptor concentration Na = 1015 cm–3 and the degree of compensation 50% was ~1.7 ns [6]. The appearance of multiuser pump–probe facilities with infrared FELs providing a radiation-pulse duration in the range 10–100 ps made it possible to substantially extend the experimental capabilities. Specifically, the
trapping time in p-Ge at different levels of doping and compensation was studied [7], and from the data obtained, it was possible to determine the parameters required
Data Loading...
