Near band-edge optical absorption in pure GaAs

175

Luminescence, excitation, and photoconductivity spectra of epitaxial n-and p-type BaAs at 1.6 K are measured with high resolution, using very low intensity of excitation. Under this condition, it is found that the (DO, X ) bound exciton emission is split into two components, and that further structure is observable between the (D", X) and the luminescence band, recently attributed to lower branch polariton emission. In particular, two very sharp lines are seen z 0.5 meV above the (Do, X) emission. These lines are observed in all our samples, and their intensities seem to be related to the strength of the (Do, X) line. Analysis of the excitation spectra lead to the identification of three emission lines. These are the n = 2 free exciton transition, the two-electron transition of the ( D O , X) complex with the donor left in the n = 3 excited state, and most probably the n = 2 donor-to-valence band transition.Mit hoher Auflosung wurden die Lumineszenzspektren, Anregungsspektren und Photoleitungsspektren von n-und p-leitendern epitaktischem GaAs bei 1,6 K gemessen. Bei Verwendung sehr geringer Anregungsintensitliten spaltet die Linie des am Donator gebundenen Exzitons (Do, X) auf und weitere Feinstruktur wird sichtbar zwischen (Do, X) und der Emissionslinie, die kurzlich dem unteren Polaritonenast zugeschrieben wurde. Insbesondere werden in allen Proben zwei sehr scharfe Linien etwa 0,5 meV oberhalb der (Do, X)-Linie beobachtet. Diese Linien scheinen in ihrer Intensitlit mit der (Do, X)-Emission korreliert zu sein. Die Analyse der Anregungsspektren erlaubt die Zuordnung dreier Emissionslinien. Dies sind der n = 2-Exzitoneniibergang, der Zwei-Elektronen-ubergang des (Do, X)-Komplexes, wobei der Donator im n = 3-Zustand verbleibt, und schlieBlich der n = 2-DonatorValenzband-Vbergang .

Section: Lines a B And Csupporting

confidence: 57%

Luminescence and Excitation Spectra of Exciton Emission in GaAs

Heim

Hiesinger

1974

175

“…[l] established r = 11 meV from t h e analysis of the electroreflectance spectrum measured at 77 K. Pond and Handler [2] obtained approximately the same value of the broadening parameter a t 283 K. The reflectance spectra of pure GaAs yield T = 5 nieV at 297 K [3]. The lowest value of I' = 0.17 meV in this material was obtained by Hill [4] from the analysis of the absorption spectrum a t 1.38 K. The data available in literature prove an obvious fact that the parameter r depends on temperature and purity of the sample under investigation. But these data do not provide detailed information on the shape of this dependence.…”

Section: Introductionmentioning

confidence: 93%

The influence of phonons and impurities on the broadening of excitonic spectra in gallium arsenide

Alperovich

Zaletin

Kravchenko

et al. 1976

“…I t s position nearly exactly coincides with the well expressed peculiarity in Hill's [7] and Sell's [24] absorption spectra, which points to their unquestionable relationship. This peculiarity (1.5174 eV) was ascribed by Sell [24] to the free hole --f band electron transition in the n = 2 state of a neutral donor, DT + hv 3 DX, z + h .…”

Section: The D-limementioning

confidence: 51%

“…1 the PC (Fig. 1, curve 1) and P L spectra of the A-type crystals and Hill's absorption spectrum [ 7 ] are shown.…”

Section: Photoconductivitymentioning

confidence: 99%

“…Besides, the PL-spectrum shape allows to make a conclusion whether the near-surface region of a semiconductor, playing an important role in PC, is perfect. Since we failed to register a structure higher than the n = 1 state of FE in the PL spectra observed by us, Hill's absorption spectra [7] were used for the identification of higher-energetic FS lines (Fig. 1). I n crystals of the B-type the position of the main maximum k in P C is not constant and varies from 1.512 to 1.514 eV from sample to sample.…”

Section: Photoconductivitymentioning

confidence: 99%

See 1 more Smart Citation

Exciton Effects in Photoconductivity of GaAs

Kravchenko

Nazintsev

1980

Photoconductivity (PC) and photoluminescence (PL) spectra are investigated on epitaxial Ga$s a t T = 2 to 50 K. According to the way excitons manifest themselves, two types of crystals, A and B, are discovered in the PC spectra. In crystals of A-type, the photocurrent maximum corresponds to the exciton maximum in absorption spectra; in crystals of B-type, vice versa, the photocurrent minimum corresponds to the esciton maximum in the absorption spectra. In crystals of A-type the position of the earlier observed lines b (1.5154 eV) and d (1.5175 eV) is defined more precisely, and new lines a (1.5141 eV), c (1.5167 eV), and e (1.5185 eV) are registered. Anidentification of the observed lines is carried out. The influence of temperature and additional illumination on the PC spectra of crystals of both types is studied. The results of investigation show the decisive role of the recombination processes in the volume and on the surface of a crystal in the formation of excitons in PC spectra. Ha 3IIMTaKCHaJlbHOM GaAs IIpH T = 2 HO 50 K I43yqaBTCR CIIeKTpbI ( P O T O~~O B O~H M O C T H (@n) I4 @OTOJIX)MHHeCUeHUHH (an