Journal of Physical Studies 2(4), 555–566 (1998) DOI: https://doi.org/10.30970/jps.02.555 A STUDY OF THE NATURE OF THE EMISSION CENTRES AND MECHANISMS OF RADIATIVE RECOMBINATION IN SEMI-INSULATING GaAs CRYSTALS

V. G. Komarov⁽¹⁾, F. V. Motsnyi⁽¹⁾, V. F. Motsnyi⁽¹⁾, O. S. Zinets^(2)
(1)Institute of Physics of Semiconductors of the National Academy of Sciences of Ukraine,
45 Nauky Pr., Kyiv, UA–252028, Ukraine
⁽²⁾Institute for Nuclear Research of the National Academy of Sciences of Ukraine,
47 Nauky Pr., Kyiv–22, UA–252022, Ukraine

The low temperature photoluminescence spectra of semi–insulating GaAs crystals grown by Czochralski method at different technological conditions have been studied. One of the main background impurities in such materials is carbon. The traditional high temperature annealing of semi–insulating GaAs wafers significantly aggravates their structure perfection because near the surface the creation of conductive layers with the thickness of several microns takes place. The fine structure of the bands of 1.514 and 1.490~eV has been registered. This structure caused by a) polariton emission from upper and low polariton branches; b) radiative recombination of free holes on shallow neutral donors ($D^0$, $h$); c) radiative recombination of excitons bound to shallow neutral donors ($D^0$, $X$) and to shallow carbon acceptors (C$^0_{\rm As}$, $X$); d) excitons bound to the point structure defects ($d$, $X$); e) electron transitions between the conduction band and shallow neutral carbon acceptor; f) the electron transitions between donor–acceptor pairs in which carbon and possibly zinc are acceptors in the ground 1$S_{3/2}$ state. The lux–intensity dependencies of the polariton emission from upper polariton branch and photoluminescence of ($D^0$, $h$), (C$^0_{\rm As}$, $X$), ($d$, $X$) complexes are in good agreement with the theory. It is shown that one of the best available semi–insulating GaAs materials is a new commercial AGCP–5V material which differs from others by considerable concentration of shallow donors and new acceptors alongside of the known shallow C$^0_{\rm As}$ acceptor centres.

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