Ge–Sb–S–Se–Te amorphous chalcogenide thin films towards on-chip nonlinear photonic devices

Abstract

Thanks to their unique optical properties Ge–Sb–S–Se–Te amorphous chalcogenide materials and compounds offer tremendous opportunities of applications, in particular in near and mid-infrared range. This spectral range is for instance of high interest for photonics or optical sensors. Using co-sputtering technique of chalcogenide compound targets in a 200 mm industrial deposition tool, we show how by modifying the amorphous structure of GeSb w S x Se y Te z chalcogenide thin films one can significantly tailor their linear and nonlinear optical properties. Modelling of spectroscopic ellipsometry data collected on the as-deposited chalcogenide thin films is used to evaluate their linear and nonlinear properties. Moreover, Raman and Fourier-transform infrared spectroscopies permitted to get a description of their amorphous structure. For the purpose of applications, their thermal stability upon annealing is also evaluated. We demonstrate that depending on the GeSb w S x Se y Te z film composition a trade-off between a high transparency in near- or mid-infrared ranges, strong nonlinearity and good thermal stability can be found in order to use such materials for applications compatible with the standard CMOS integration processes of microelectronics and photonics.

Amorphous-to-Crystal Transition in Quasi-Two-Dimensional MoS2: Implications for 2D Electronic Devices

“…In general, sulfur-based amorphous chalcogenides, also called chalcogenide vitreous semiconductors, or chalcogenide glasses, have negligible absorption in the transparent spectral region. 34 This fact has been stressed as very unusual by Sir Nevill Mott in his Nobel lecture 35 because transparent means having an energy gap between the conduction and valence bands and the formation of such a gap has been traditionally attributed to the presence of the long-range order, which does not exist in amorphous materials. Consequently, it was demonstrated that the formation of the energy gap is determined by the short-range order and, in particular, is due to the presence of saturated covalent bonds.…”

Screening Switching Materials with Low Leakage Current and High Thermal Stability for Neuromorphic Computing

“…[ 1 ] Throughout the previously reported OTS materials, the material systems are mainly ternary, quaternary or even more elements that inevitably encounter the problem of composition segregation during the cycle operation. [ 24,25,26 ] Hence, we perform a systematic materials screening of chalcogenides from the periodical table of elements using aforementioned three essential criteria‐few elements, wide bandgap and high T c . The cations of these chalcogenides are from group III to V located at mental‐semiconductor boundary, as shown in Figure a, which were widely used or doped in phase change memories (PCMs).…”

Evaluating Ovonic Threshold Switching Materials with Topological Constraint Theory

“…Our calculations indicate that the peak at 125 cm –1 may be due to vibrational modes associated with GeTe 4 tetrahedra connected by Te–Te bonds (134 cm –1 ). Other groups have suggested that this peak is due to GeTe-defective octahedra (128 cm –1 ) , or GeTe 4 -stretching modes (131 cm –1 ) . While the specific atomic structure of GeTe alloys is an interesting subject in its own right, it is important to note that we will be focusing on Se-rich quaternary GeSeAsTe alloys.…”