Selective growth of fully relaxed GeSn nano-islands by nanoheteroepitaxy on patterned Si(001)

In this letter, we explore in detail the potential ofnanoheteroepitaxy to controllably fabricate high quality GeSn nano-structures and to further improve the crystallinity of GeSn alloys directlygrown on Si(001). The GeSn wasgrown bymolecular beam epitaxy at relatively high temperatures up to 750  °C on pre-patterned Si nano-pillars embedded in a SiO2 matrix. The best compromise between selective GeSngrowth and homogenous Sn incorporation of 1.4% was achieved at agrowth temperature of 600  °C.X-ray diffraction measurements confirmed that ourgrowth approach results in both fully relaxed GeSn nano-islands and negligible Siinterdiffusion into the core of thenanostructures. Detailedtransmission electron microscopy characterizations show that only the small GeSn/Si interface area reveals defects, such as stacking faults. Importantly, the main part of the GeSn islands is defect-free and of high crystalline quality. The latter was further demonstrated by photoluminescence measurements where a clear redshift of the direct ΓC- ΓV transition was observed with increasing Sn content.

Source: Applied Physics Letters - November 14, 2016 Category: Physics Authors: V. Schlykow, W. M. Klesse, G. Niu, N. Taoka, Y. Yamamoto, O. Skibitzki, M. R. Barget, P. Zaumseil, H. von K änel, M. A. Schubert, G. Capellini and T. Schroeder Source Type: research