1Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 2College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049 3Beijing Key Laboratory of Inorganic Stretchable and Flexible Information Technology, Beijing 100083 4Institute of Physics, Chinese Academy of Sciences, Beijing 100190
Abstract：The performance of type-II superlattice (T2SL) long-wavelength infrared devices is limited by crystalline quality of T2SLs. We optimize the process of growing molecular beam epitaxy deposition T2SL epi-layers on GaSb (100) to improve the material properties. Samples with identical structure but diverse In/Ga beam-equivalent pressure (BEP) ratio are studied by various methods, including high-resolution x-ray diffraction, atomic force microscopy and high-resolution transmission electron microscopy. We find that appropriately increasing the In/Ga BEP ratio contributes to improving the quality of T2SLs, but too large In BEP will much more easily cause a local strain, which can lead to more InSb islands in the InSb interfaces. The InSb islands melt in the InSb interfaces caused by the change of chemical potential of In atoms may result in the "nail" defects covering the whole T2SLs, especially the interfaces of GaSb-on-InAs. When the In/Ga BEP ratio is about 1, the T2SL material possesses a lower full width at half maximum of $+$1 first-order satellite peak, much smoother surface and excellently larger area uniformity.
Ledentsov N N, Shchukin V A, Grundmann M, Kirstatedter N, Böhrer J, Schmidt O, Bimberg D, Ustinov V M, Egorov A Y and Zhukov A E 1996 Phys. Rev. B54 8743
2020, Vol. 37 
