Germanium-tin alloys: applications for optoelectronics in mid-infrared spectra

Abstract

We summarize our work of the optoelectronic devices based on Germanium-tin (GeSn) alloys assisted with the Si 3 N 4 liner stressor in mid-infrared (MIR) domains. The device characteristics are thoroughly analyzed by the strain distribution, band structure, and absorption characteristics. Numerical and analytical methods show that with optimal structural parameters, the device performance can be further improved and the wavelength application range can be extended to 2~5 μm in the mid-infrared spectra. It is demonstrated that this proposed strategy provides an effective technique for the strained-GeSn devices in future optical designs, which will be competitive for the optoelectronics applications in mid-infrared wavelength.

Enhanced photo-sensitivity in a Si photodetector using a near-field assisted excitation

“…By using the effect of the near-field excitation shown here, the photodetector and solar cell with a higher efficiency could be realized 28 . As for the improvement of the photo-excitation in an indirect bandgap material, the band engineering method has been proposed for Ge, in which by introducing the strain, the band diagram turned to be the direct bandgap and resulted in the improvement of the photoexcitation 29 . Since the possibility of direct transition by the ONF, which is not inherent in Si, it can be utilized in various other applications, including photodetectors, light-emitting devices, H 2 generation, using the indirect bandgap materials including Ge 30 , SiC 31 , diamond 32 , and multilayer MoS 2 33,34 .…”

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

“…The silicon photonics has seen within last decades a strong increase in the research interest in development of IV-group direct band gap semiconductors. In this context, GeSn alloys, ecofriendly and CMOS-compatible materials, evolved as a realistic alternative to the III−V and chalcogenide compounds that dominate the actual IR and mid-IR photonic market. − An important progress was obtained by developing efficient light sources and lasers based on the transition from indirect to direct band gap in crystalline GeSn, by increasing the Sn concentration above 6–8%, as earlier predicted. − However, the growth of high-crystalline quality SiGeSn alloys with high Sn concentrations, about 10%, being hampered by the low thermodynamic miscibility of Sn with Ge and Si, required technological progress in growing metastable (Si)­GeSn epitaxial layers . Sn atoms are placed substitutionally in the Ge lattice with the same diamond cubic crystalline symmetry of semimetal (negative band gap) α-Sn allotropic phase.…”

Recent improvement of silicon absorption in opto-electric devices

“…Further improvements of Si-based opto-electronic devices may be achieved by combining and optimizing these effects. Recently, the band engineering method was proposed to enhance the absorption in another indirect band-gap material (Ge) 58 . Similar investigations have been made in other indirect band-gap materials including InSe [59][60][61] and MoS 2 62,63 .…”