Magnetophotoluminescence studies of In_xGa_1 xAs_1 yN_y: a measurement of the electron effective mass, exciton size, and degree of carrier localization

Abstract

Photoluminescence (PL) under a magnetic field (B = 0–12 T) has been employed to determine the electron effective mass, me*, exciton radius, rexc, and degree of localization of carriers in InxGa1−xAs1−yNy/GaAs heterostructures. This study concerns nitrogen concentration values spanning from a very dilute (y<0.1%) to a full alloy (y = 5%) limit and indium concentrations x from 0% to . For indium-free samples, we find that me* and rexc undergo a sudden increase and squeezing, respectively, for . For indium-containing samples (), me* and rexc show a sudden variation similar to that for x = 0 but shifted to much higher N concentration (). In addition, in the N alloy limit the temperature dependence of the B-induced shift of the PL peak position reveals that radiative recombination at low temperature is not excitonic.

Charge separation and temperature-induced carrier migration in Ga1−xInxNNuytten1, Hayne2, Bansal3 et al. 2011Phys. Rev. B

“…Thus, a plausible reason to account for the change in the exciton wave function extent is a decrease in μ when going from Sample A to Sample B. However, we do not expect large differences in mass for these nitrogen concentrations, 24 and the data in Fig. 4 show an almost identical slope of the E cm versus B curve in the high-field regime, suggesting no difference in μ between Samples A and B.…”

“…6,9 Hence, the effect of carrier localization is expected to be much stronger in Sample A, while the period of the modulation is larger in Sample B. The result is that, in both samples, the electrons may be trapped by nitrogen-rich 24,31 regions, while the holes may only be localized in In-rich parts of the sample, separating them from electrons in the N-rich regions at low temperatures in an out-of-phase manner (Fig. 7).…”

Carrier masses and band-gap temperature sensitivity in Ga(AsBi) alloys

“…The carrier effective mass is a band-structure parameter highly sensitive to the fractional Γ-character (and symmetry) of the band edges of a semiconductor alloy, and, in turn, to the modifications induced by isoelectronic impurities on the host band-structure. Carrier masses are commonly determined by magneto-PL spectroscopy [45,49,50], which is also a very useful tool to discriminate and quantify the degree of delocalization of the states involved in the recombination [51,52]. Magneto-PL measurements were performed, therefore, on the whole series of samples to investigate the effects Bi-incorporation has both on the valence and on the conduction states of GaAs.…”

Computational modeling and analysis of quantum dots

“…We can describe electron motion in a quantum dot by substituting the mass of a free electron with the effective mass of the electrons (holes) of the host material in the Hamiltonian m e,h → m * e,h . This is called the effective mass approximation [Polimeni et al, 2004, Tablero, 2005, Lee et al, 2005, Li et al, 1996, Heidari et al, 2007.…”