ABSTRACT
Figure 1 shows the PL spectra taken at 15 K for two different [Ill ]A lnGaAs QW structures with 19 % (JK254) and 23 % (JK247) of In. The Full Width at Half Maximum (FWHM) values are 9.9 meV and 12 meV, which correspond to well width fluctuations of only ±I monolayer (ML) and ±1.5 ML, respectively. It should be noted that for [III] strained QWs and conventional [100] QWs with the same interfacial roughness, relatively larger PL FWHM values should be expected for the [III] QWs due to the presence of the PE field in these wells. The excellent interfacial properties of the [Ill ]A QWs are confirmed by TEM observations. Figure 2 shows the interfaces of the double confinement QW with a PL FWHM of9.9 meV obtained in the 002 dark field condition. The heterointerfaces between the lnGaAs and GaAs layers show low roughness and the interfaces between the AlGaAs and GaAs are excellent. The TEM image shows that there is no evidence of dislocation formation in the strained InGaAs layer. The HRXRD analysis also confirms that the [Ill ]A strained InGaAs QW is pseudomorphic. Figure 3 shows the HRXRD profiles and the theoretical curves for JK247 whose PL spectrum is shown in Fig. I. From both the asymmetric (422) and symmetric (333) reflections it is proven that the strained QW is pseudomorphic. The HRXRD simulations provided the well width and In content of the structures given in Table 1.
