Heterogeneously-Grown Tunable Tensile Strained Germanium on Silicon for Photonic Devices

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• 作者：Michael Clavel ; Dzianis Saladukha ; Patrick S. Goley ; Tomasz J. Ochalski ; Felipe Murphy-Armando ; Robert J. Bodnar ; Mantu K. Hudait
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：December 9, 2015
• 年：2015
• 卷：7
• 期：48
• 页码：26470-26481
• 全文大小：923K
• ISSN：1944-8252

文摘

The growth, structural and optical properties, and energy band alignments of tensile-strained germanium (蔚-Ge) epilayers heterogeneously integrated on silicon (Si) were demonstrated for the first time. The tunable 蔚-Ge thin films were achieved using a composite linearly graded In_xGa_1鈥?i>xAs/GaAs buffer architecture grown via solid source molecular beam epitaxy. High-resolution X-ray diffraction and micro-Raman spectroscopic analysis confirmed a pseudomorphic 蔚-Ge epitaxy whereby the degree of strain varied as a function of the In_xGa_1鈥?i>xAs buffer indium alloy composition. Sharp heterointerfaces between each 蔚-Ge epilayer and the respective In_xGa_1鈥?i>xAs strain template were confirmed by detailed strain analysis using cross-sectional transmission electron microscopy. Low-temperature microphotoluminescence measurements confirmed both direct and indirect bandgap radiative recombination between the 螕 and L valleys of Ge to the light-hole valence band, with L-lh bandgaps of 0.68 and 0.65 eV demonstrated for the 0.82 卤 0.06% and 1.11 卤 0.03% strained Ge on Si, respectively. Type-I band alignments and valence band offsets of 0.27 and 0.29 eV for the 蔚-Ge/In_0.11Ga_0.89As (0.82%) and 蔚-Ge/In_0.17Ga_0.83As (1.11%) heterointerfaces, respectively, show promise for 蔚-Ge carrier confinement in future nanoscale optoelectronic devices. Therefore, the successful heterogeneous integration of tunable tensile-strained Ge on Si paves the way for the design and implementation of novel Ge-based photonic devices on the Si technology platform.