Wafer-scale mono-crystalline GeSn alloy on Ge by sputtering and solid phase epitaxy

Abstract

Germanium-tin (GeSn) alloys are of great interest for electronic as well as photonic applications, and their integration on a group-IV (Si or Ge) platform. This letter describes a low deposition temperature, process integration-friendly, high throughput and low cost approach for growing device-quality GeSn epilayers on Ge substrates. Mono-crystalline, wafer-scale GeSn alloy with 3.4% Sn content was grown on Ge (100) substrates by sputtering an amorphous GeSn layer followed by solid phase epitaxy (SPE) at . Deposition of amorphous layers at room temperature enables incorporation of high bulk Sn content in GeSn epilayers. SPE of the amorphous layer at leads to a strained, high quality GeSn epilayer having a low full width half maximum of , root mean square surface roughness of 0.3 nm and a good GeSn/Ge interface as confirmed through extensive x-ray diffraction measurements, atomic force microscopy and transmission electron microscopy imaging. Additionally, an SiO2 capping layer employed during SPE is shown to prevent Sn out-diffusion and segregation at the surface. To examine electrical properties for potential applications of the GeSn/n-Ge heterostructure, metal/GeSn/n-Ge vertical contact diodes and metal/GeSn circular transfer length method contact structures were fabricated and electrically characterized.

Growth of relaxed GeSn film with high Sn content via Sn component-grade buffer layer structure

“…Figures 5(b Thermal stability of high-Sn-composition GeSn films is critical for the fabrication of GeSn devices. To investigate the thermal stability of the GeSn alloys, samples A and C Compared with CVD and MBE epitaxial technology, sputtering technology has the advantages of low cost, little toxicity and mass production [35][36][37]. Due to the strain-relaxation enhancement mechanism in CVD [16], relaxed GeSn film can be grown by CVD and optically pumped GeSn lasers with a Sn composition up 20% have been reported [9].…”

“…Sample A was stable below 300 • C while sample C was stable below 250 • C, which are relatively low temperatures for complementary metal oxide semiconductor operations. This indicates that, in this study, the relaxed GeSn alloys with high Sn composition have poor thermal stability and need to be improved by further research to meet the requirements of the device manufacturing process.Compared with CVD and MBE epitaxial technology, sputtering technology has the advantages of low cost, little toxicity and mass production[35][36][37]. Due to the strain-relaxation enhancement mechanism in CVD[16], relaxed GeSn film can be grown by CVD and optically pumped GeSn lasers with a Sn composition up 20% have been reported[9].…”

Study on crystallization mechanism of GeSn interlayer for low temperature Ge/Si bonding

“…For thermal boundary conditions, the relaxation state at 300 ℃ is set as the initial state, and the RT is set to the nal state. The involved material parameters are listed in Table I [22,23]. The amorphous GeSn immediate layer is assumed isotropic and the coe cient of expansion of GeSn was calculated using linear interpolation [24].…”

Theoretical Investigation of Strain-Adjustable Ge0.92Sn0.08 Light-Emitting Diodes With Giant Magnetostrictive Stressor for Short-Wave Infrared Light Source

“…Group-IV GeSn is compatible with CMOS processes and can be transformed into direct bandgap alloy, which is the promising material for short-wave infrared (SWIR) light source [4,5]. The Γ valley decreases faster than the L valley with the increase of introduced Sn, and the indirect-to-direct transition will be realized when Sn content reaches 7.1% [6][7][8][9], which can extend the applications such as electro-magnetic spectrum -based night vision and the optic window for the transcranial light [10][11][12][13]. However, it is difficult to increase the Sn content by more than 14% for light source material due to the Sn segregation caused by the low solid solubility (< 1%) of Sn in Ge and the large lattice mismatch [14][15].…”