Optical Studies of Free and Bound Excitonic States in GaSb Evidence for Deep A⁺‐Complexes

Abstract

The energies of the free exciton and of four excitons bound to neutral acceptors (Ao, X) are determined by either reflection, absorption, or emission with high purity p-type GaSb. The data give evidence that bound excitons may be described alternatively as an electron bound by a donor-like A+-centre. For one particular deep A+-centre, transitions from neutral donor states to that A+-centre are observed besides the bound exciton decay. p-GaSb is especially favourable for observing deep A+-centres, because of the position of the Fermilevel. Conditions under which they may be observable for other 111-V compounds are discussed.Die Energien des freien Exzitons und von vier an neutrale Akzeptoren gebundenen Exzitonen (Ao, X) wurden aus Reflexions-, Absorptions-und Emissionsspektren von hochreinem p-leitendem GaSb bestimmt. Die MeBergebnisse deuten darauf hin, daB gebundene Exzitonen als Donator-iihnliche A+-Zentren mit einem gebundenen Elektron beschrieben werden konnen. Bei einem bestimmten, tiefen A+-Zentrum wurden neben dem Zerfall des gebundenen Exzitons die Rekombination von Elektronen von neutralen Donatorzustlnden mit dem Loch dieses A+-Zentrums beobachtet. p-GaSb ist wegen der Lage des. Ferminiveaus fur die Beobachtung tiefer A+-Zustiinde besonders geeignet. Es werden Bedingungen diskutiert, unter denen auoh in anderen 111-V-Halbleitern A+-Zustiinde beobachtbar sein sollten.

Optical characterization of gallium antimonide highly doped with manganese

“…in Refs. [15,17], and (2) a supposition that the maximum of band A M corresponds to the position of the Mn-acceptor level. E Mn A ¼ 15:1215:6 meV was obtained.…”

Influence of temperature ramp on the materials properties of GaSb grown on ZnTe using molecular beam epitaxy

“…Low-temperature PL of GaSb has been well studied by many authors, [8][9][10][11][12][13] and there are about 20 reported transitions in the range of 680-810 meV. [8][9][10][11] Among these transitions, three main PL lines are often observed and these have been discussed in optical characterization measurements: (i) A PL line with maximum at 796 meV, denoted as "BE" or "BE4," which is considered as an emission of an exciton bound to a nonspecified neutral acceptor.…”

“…[8][9][10][11] Among these transitions, three main PL lines are often observed and these have been discussed in optical characterization measurements: (i) A PL line with maximum at 796 meV, denoted as "BE" or "BE4," which is considered as an emission of an exciton bound to a nonspecified neutral acceptor. 12 (ii) A PL line with maximum at 777 meV, denoted as the "A" line, which is ascribed to recombination at a native acceptor level (A) via band-acceptor (BA) or donor-acceptor pair (DAP) transitions. 8,13 (iii) A PL line with maximum around 758 meV, denoted as the "B" line, which is interpreted as a transition from another acceptor level (B).…”

“…4, sample #1 has very weak emissions from 793 to 807 meV, which are ascribed to the transitions from bound excitons. 9,[11][12][13] The dominant PL feature is the emission in the range of 570-780 meV with peaks positioned around 637 and 728 meV. Since the growth of GaSb for sample #1 is carried out at lower temperature (T g ¼ 380 C), rather than the normal temperature (T g ¼ 470 C), this broad emission is therefore attributed to optical transitions related to defects generated during the low-temperature growth.…”

Origin of the photoluminescence line at 0.8 eV in undoped and Si-doped GaSb grown by MOVPE

“…Moreover, it is experimentally established that the PL spectra of GaSb epitaxial layers grown under conditions of Sb deficiency [10] are always dominated by the BE1, BE2, BE3 and A lines. In contrast, when grown in Sb-rich conditions, the GaSb exhibits PL spectra dominated by the BE4 line [11,12]. Due to the specific features of BE4, one may assume that an increase in the BE4 intensity with respect to the A line intensity implies a decrease in the concentration of one of the components in the (Ga Sb -V Ga ) complex.…”