Simultaneous experimental evaluation of In and N concentrations in InGaAsN quantum wells

Abstract

Articles you may be interested inStrain-induced nitrogen incorporation in atomic layer epitaxy growth of InAsN/GaAs quantum wells using metal organic chemical vapor deposition Appl. Phys. Lett. 95, 051102 (2009); A comparison of photoluminescence properties of InGaAs/GaAs quantum dots with a single quantum wellWe propose a method that solves the problem of the independent determination of the indium and nitrogen concentrations in a strained quaternary InGaAsN superlattice. The method is experimentally based on the simultaneous measurement: ͑i͒ of the tetragonal lattice distortion of the unit cell from high resolution micrographs and ͑ii͒ of the intensity of the chemically sensitive ͑002͒ reflection from dark field images. As an example, we evaluate InGaAsN quantum wells with a nominal N concentration of 1.7% and with In concentrations of 10%, 20%, or 35%. We reveal local fluctuations of the In and N concentrations over distances down to 4 nm with a sensitivity of 0.1% for N and 1% for In fluctuations in this distance range.

Composition fluctuations in dilute nitride (Ga,In)(N,As)/GaAs heterostructures measured by low-loss electron energy-loss spectroscopy

“…However, this composition fluctuation cannot be appropriately reflected in the chemically sensitive (002) darkfield image. According to the calculation of the dark-field intensity I 200 in dependence of the compositions (Grillo et al, 2001;Chauveau et al, 2003b), we find that the present N and In concentrations are located at the broad minimum of the intensity, where variations in the composition cannot be reliably detected. Therefore, the small composition fluctuation in this epilayer cannot be observed in the (002) dark-field image.…”

“…Among these techniques, the EELS in the TEM offers the unique combination of very high spatial resolution and the ability to provide information upon chemical bonding of conventional III-V semiconductors (Gutiérrez-Sosa et al, 2002;Keast et al, 2002;Sanchez et al, 2004;Sanchez et al, 2005;Leifer, 1999). Presently however, there are only few studies in the literature concerning measurements of N and In concentrations of dilute nitrides with TEM and EELS Grillo et al, 2001;Albrecht et al, 2002;Chauveau et al, 2003b;Litvinov et al, 2004). The applied methods, which were used in all of these reports can be summarized in two categories: (i) the conventional (002) dark-field and high-resolution TEM methods (Grillo et al, 2001;Albrecht et al, 2002;Chauveau et al, 2003b;Litvinov et al, 2004), which can be used to investigate the N and In distribution along the growth direction, ([001] in most cases), and which require a rather homogeneous lateral elemental distribution relative to the TEM specimen thickness; (ii) the energy-filtered imaging method (Sanchez et al, 2004;Sanchez et al, 2005;Leifer, 1999;Gass et al, 2004), such as low-loss EELS combined with elemental mapping with the In 4d signal.…”

Interface properties of (Ga,In)(N,As) and (Ga,In)(As,Sb) materials systems grown by molecular beam epitaxy

“…Grillo et al shown that the combined analysis of (i) the intensity of the (0 0 2) DF-TEM images and (ii) the measurement of the tetragonal lattice distortion from experimental high-resolution TEM (HR-TEM) solves the problem, thus leading to an unambiguous and independent determination of the In and N content [12]. Finally, in the case of the more complicated NAC InAs/GaSb interfaces, we propose an innovative method for the determination of the chemical abruptness that will be presented in Section 3.3.…”

Influence of structural nonuniformity and nonradiative processes on the luminescence efficiency of InGaAsN quantum wells

“…The In and N distributions, as well as the thickness fluctuations in the QWs, were analyzed by a combined evaluation: ͑i͒ of the tetragonal lattice distortion and ͑ii͒ of the intensity of the chemically sensitive ͑002͒ reflection in respective dark-field images of the same areas. 6 TEM images of unannealed SQWs grown at 402, 429, and 453°C are displayed in Fig. 1͑a͒.…”