Highlights SiGeC Group.

Free-running Sn precipitates: an efficient phase separation mechanism for metastable Ge1−xSnx

Scientific Reports 7, 16114 (2017)
H. Groiß, M. Glaser, M. Schatzl, M. Brehm, D. Gerthsen, D. Roth, P. Bauer, F. Schäffler



(a) Cross-sectional SEM image of a solidified Sn droplet that separates the re-deposited Ge-layer on the left side from the intact GeSn film on the right side. To protect the droplet during FIB-preparation the sample was covered with e-beam- and FIB-induced Pt-deposits that appear as dark- and light-grey conformal layers (indicated in the right inset: Pt-deposit and Ge-Sn are separated by a dotted line). The insets show at the right side the pristine GeSn layer and on the left side the re-deposited Ge film with a small Sn-droplet remaining in a {111} pit (white arrow). The original GeSn-Ge interface is indicated by a dashed line. (b) Schematic view of the proposed phase separation process induced by the liquid Sn droplet.

Enhanced Telecom Emission from Single Group-IV Quantum Dots by Precise CMOS-Compatible Positioning in Photonic Crystal Cavities

ACS Photonics 4, 665–673 (2017).
M. Schatzl, F. Hackl, M. Glaser, P. Rauter, M. Brehm, L. Spindlberger, A. Simbula, M. Galli, T. Fromherz, F. Schäffler



Figure 1. Layout of the single-dot photonic crystal cavities. (a) Scanning electron micrograph of a complete PCR structure with a single Ge QD in the center of the L3 cavity (inset), fabricated in one growth and processing run. The QD array with twice the period of the PC array remains only outside the photonic structure. The inset reveals the modifications of the air hole positions adjacent to the cavity of our adapted high-Q design. (b) Representative set of six simultaneously fabricated L3 cavities in which the Ge QD position (marked by an arrow) was varied along the horizontal center line of the cavity. As a reference, one of the cavities was fabricated without a pit for QD nucleation; that is, it contained only the Ge wetting layer (last frame). (c) Schematic view (not to scale) of a single QD positioned in the calculated field energy density maximum of the M2 cavity mode. The structural components of the single-dot emitter system are indicated. Note that the dot position is determined by the pit in the prepatterned substrate, as described in the Methods section. The displayed dot shape was modeled on an atomic force micrograph.