The time behaviour of the radiative recombination of nitrogen-doped GaP is investigated a t pulsed intense optical excitations and low temperatures (2' = 2 and 27 K). The decay behaviour of the luminescence intensities corresponding to the electron-hole liquid (EHL) and the coexisting lowdensity phase (LDP) is found for all nitrogen concentrations (nN = 2 x 10'' to 2.9 x 10'8 ~3 1 1~~) to be nonexponential. It is interpreted as a consequence of interactions between both coexisting phases. A model is introduced where the EHL is fed by the LDP continuously. It describes the observed decay of the luminescence very well, even for different nitrogen concentrations and different excitation intensities.Es wird das Zeitverhalten der strahlenden Rekombination von stickstoffdotiertern GaP unter intensiver optischer Impulsanregung bei T = 2 und 27 K untersucht. Das Abklingverhalten der Lumineszenzintensititen, die der Elektron-Loch-Fliissigkeit (EHL) sowie der koexistierenden Niederdichtephase (LDP) entsprechen, ist fur alle hier untersuchten Stickstoffkonzentrationen (TLN = 2 x 10'' bis 2,9 x 10l8 nichtexponentiell. Es wird als Folge der Wechselwirkungen zwischen beiden koexistierenden Phasen angesehen. Ein entsprechendes Modell wird vorgeschlagen, wobei die EHL laufend von der LDP aufgefiillt wird. Es beschreibt das Abklingverhalten der Lumineszenz beider koexistierenden Phasen fur unterschiedliche Stickstoffkonzentrationen nnd Anregungsintensitaten sehr gut.
The radiative recombination of isoelectronic (nitrogen)-doped GaP is investigated a t high optical excitations and low temperatures (5" = 2 K). Extensive experimental results on the luminescence in dependence on the excitation intensity, the nitrogen concentration (N,) and its decay behaviour are presented. At low nitrogen concentrations ( N N 2 lOI7 ~m -~) and highest excitation levels the radiative recombination from a n electron-hole liquid (EHL) accompanied by momentum conserving phonons analogous to undoped GaP can be confirmed. At higher nitrogen concentrations in the range of N , = 3 to 8 X l O I 7 a radiative no-phonon transition appears from an E H L induced by the isoelectronic impurity nitrogen. The influence of the latter on the energy of the E H L is studied. The rising nitrogen density yields a n increase in the EHL work function. At medium and high nitrogen concentrations (Ar, 5 lo1* in-^) a further up to now uaknown luminescence band becomes visible arising from the radiative recombination of a "plasma-like" phase which is strongljinfluenced by the isoelectronic impurity nitrogen and coexists with the EHL. I t s density ( n P 1 ) depends on the nitrogen concentration. The use of a simplified model basing on the polarization energy of the carriers caused by the short-range isoelectronic potential enables the nnderstanding of the experimental findings.
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