The effects of strain and composition on the conduction-band offset of direct band gap type-I GeSn/GeSnSi quantum dots for CMOS compatible mid-IR light source

Abstract

The effects of strain and composition on the conduction-band offset of direct band gap type-I GeSn/GeSnSi quantum dots for CMOS compatible mid-IR light source

GeSn/SiO2 Multilayers by Magnetron Sputtering Deposition for Short-Wave Infrared Photonics

“…Alloying of Ge and Sn was the most successful method to obtain IV-group direct band gap semiconductors, as theoretically predicted and numerically computed. − The lattice strain, for example, induced by epitaxy, is an additional important factor influencing the electronic band structure of GeSn. Thus, compressive biaxial strain shifts the Sn concentration threshold for direct band gap transition to higher values, while tensile biaxial strain lowers the required Sn content and increases the light emission efficiency. ,, Beside the strain engineering and Sn alloying of Ge, in the case of low-dimensional systems such as quantum wells, nanowires, and quantum dots, the quantum confinement effect offers additional degrees of freedom, namely, band gap tuning and increase in maximum Sn concentration and optical transition probabilities for improving the device performances. ,,− …”

Epitaxial GeSn Obtained by High Power Impulse Magnetron Sputtering and the Heterojunction with Embedded GeSn Nanocrystals for Shortwave Infrared Detection

“…The GeSn alloys have been intensively studied recently with the main aim to overcome the low light emission efficiency of indirect band gap group IV Si–Ge–C semiconductors. − Limited progress was obtained by intensive studies on light emission in Si, Ge, and their alloys, such as nanocrystals (NCs), , Ge islands, Er-doping, electron–hole plasma in SiGe, or n-doped and tensile strained Ge. − A new era of Si photonics was opened by the development of high quality crystalline GeSn alloys which at Sn concentration above 8 atom % become direct band gap semiconductors through the change of the minimum of the conduction band from the L-valley to the Γ-valley. − Furthermore, the decrease and tunability of the band gap with Sn composition leads to the extension and tuning of the optical activity of these group IV semiconductors into the application relevant shortwave infrared (SWIR) of 1.4–3 μm and mid-infrared (MIR) of 3–5 μm. − The development of these new photonic materials was hindered for many years by the low miscibility of Sn with Ge and Si, thermodynamically stable for less than 1% Sn . Thus, although the direct band gap was theoretically predicted in the early 1980s, this breakthrough was only recently reported.…”