An interesting phenomenon is that only multiple satellite peaks were observed on the left-hand side of the GaAs substrate peak in the XRD pattern of QWIP with 5-nm low-temperature AlGaAs barrier. However, the satellite peak distribution is nearly symmetrical in the QWIP sample with barrier grown, all at high temperature. We

do not have a solid explanation for such phenomenon. It may possibly be related to the higher strain level in the sample containing 5-nm low-temperature AlGaAs barrier [19]. Figure 2 XRD 2 theta-scanning of (a) samples A, this website B, and C; (b) sample D; (c) sample E. Finally, to evaluate these two strategies in terms of peak absorption wavelength, samples were fabricated into 200 × 200 μm2 mesa and

then measured by the photocurrent spectrums which were performed by a Fourier transform infrared selleck chemicals llc spectrometer with multi-pass configuration. As can be seen in Figure 3, the peaks of samples E and F were identically located at 4.2 μm well meeting with the theoretic design of around 4.3 μm. However, sample D, without a 5-nm LT-AlGaAs cap layer possessed a wavelength shift of as large as 1.25 μm. According to photocurrent spectrums, the strong photocurrent signal proves the thin LT-AlGaAs barrier does not deteriorate the extraction efficiency very much. So the deposition of thin LT-AlGaAs capping layer is a promising technique to fabricate InGaAs/AlGaAs absorption-wavelength-controlled QWIP, and the

stability and reproducibility could be guaranteed as well. Figure 3 The photocurrent spectrums of samples D, E, and F. Conclusion The In composition Buspirone HCl loss was found to be a serious problem in the fabrication of InGaAs/AlGaAs QWIP devices due to its unavoidability and unrepeatability. In this study, it was demonstrated that using a thin AlGaAs layer grown at low temperature could successfully prevent the In composition from losing. Highly reproducible peak response wavelengths of InGaAs/AlGaAs QWIP demonstrate the well-controlled structural characteristics of InGaAs quantum well. Acknowledgements This work was supported by the Natural Science Foundation of China (Grant Nos. 61106013 and 61275107), the National High Technology Research and Development Program of China (Grant nos. 2009AA033101 and 2013AA031903), and the National Basic Research Program of China (Grant nos. 2010-CB327501 and 2011CB925604). References 1. Rogalski A: Recent progress in third generation infrared detectors. J Mod Opt 2010,57(18):1716–1730.CrossRef 2. Shen S: Comparison and competition between MCT and QW structure material for use in IR detectors. Microelectron J 1994,25(8):713–739.CrossRef 3. Hu W, Chen X, Ye Z, Lu W: A hybrid surface passivation on HgCdTe long wave infrared detector with in-situ CdTe deposition and high-density hydrogen plasma modification. Appl Phys Lett 2011,99(9):091101.CrossRef 4.