Abstract
This work deals with elastically strained GeSiSn films and GeSiSn islands. Kinetic diagram of GeSiSn growth at different lattice mismatches between GeSiSn and Si has been established. Multilayer periodic structures with pseudomorphic GeSiSn layers and GeSiSn island array have been obtained. The density of the islands in the GeSiSn layer reaches 1.8 ⋅ 1012 cm−2 at an average island size of 4 nm. Analysis of the rocking curves showed that the structures contain smooth heterointerfaces, and strong changes of composition and thickness from period to period have not been found. Photoluminescence has been demonstrated and calculation of band diagram in the model solid theory approach has been carried out. Luminescence for the sample with pseudomorphic Ge0.315Si0.65Sn0.035 layers in narrow range of 0.71—0.82 eV is observed with the maximum intensity near 0.78 eV corresponding to a 1.59 µm wavelength. Based on a band diagram calculation for Si/ Ge0.315Si0.65Sn0.035/Si heterocomposition, one can conclud that luminescence with a photon energy of 0.78 eV corresponds to interband transitions between the X−valley in the Si and the heavy hole subband in the Ge0.315Si0.65Sn0.035 layer.
Highlights
This work deals with elastically strained GeSiSn films and GeSiSn islands
Analysis of the rocking curves showed that the structures contain smooth heterointerfaces, and strong changes of composition and thickness from period to period have not been found
Luminescence for the sample with pseudomorphic Ge0.315Si0.65Sn0.035 layers in narrow range of 0.71—0.82 eV is observed with the maximum intensity near 0.78 eV corresponding to a 1.59 μm wavelength
Summary
На основе подбора толщины пленки GeSiSn выращены многослойные периодические структуры с псевдоморфными слоями и слоями, содержащими массив островков GeSiSn с плотностью до 1,8 ⋅ 1012 см−2 и средним размером 4 нм. Последнее время особое внимание уделяется исследованиям оптических и электронных свойств соединений GeSiSn. Как было показано ранее [1, 2], GeSn может стать прямозонным материалом с увеличением содержания Sn в решетке Ge. Для кубической решетки GeSn прямозонность возникает при содержании Sn ~9 % [3, 4]. Снизить эффект преципитации Sn можно за счет уменьшения температуры роста, введения деформаций или добавления третьего элемента, например Si. Это позволяет снизить локальное напряжение вокруг атомов Sn. Помимо преципитации, наблюдается сегрегация Sn при росте слоев GeSiSn и окислении пленок GeSn [11, 12].
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