Gold and silver diffusion in germanium: a thermodynamic approach

Abstract

Diffusion properties are technologically important in the understanding of semiconductors for the efficent formation of defined nanoelectronic devices. In the present study we employ experimental data to show that bulk materials properties (elastic and expansivity data) can be used to describe gold and silver diffusion in germanium for a wide temperature range (702-1177 K). Here we show that the so-called cBX model thermodynamic model, which assumes that the defect Gibbs energy is proportional to the isothermal bulk modulus and the mean volume per atom, adequately metallic diffusion in germanium.

Design and simulation of losses in Ge/SiGe terahertz quantum cascade laser waveguides

“…A comparison of Ag, Au and Cu on GaAs/AlGaAs THz QCLs has demonstrated that Ag provides the lowest waveguide losses and lowest lasing thresholds [38]. Au is a fast diffuser and a deep level impurity in Si, Ge and SiO 2 [39][40][41] and therefore it is incompatible with all silicon foundries that might microfabricate Ge/Si 1−x Ge x QCL devices. Ag has similar deep levels but the diffusivity in Si is 3 orders of magnitude less [39], in Ge it is two orders of magnitude less [40] and in SiO 2 is one order of magnitude less than Au for similar anneal conditions [41].…”

“…Au is a fast diffuser and a deep level impurity in Si, Ge and SiO 2 [39][40][41] and therefore it is incompatible with all silicon foundries that might microfabricate Ge/Si 1−x Ge x QCL devices. Ag has similar deep levels but the diffusivity in Si is 3 orders of magnitude less [39], in Ge it is two orders of magnitude less [40] and in SiO 2 is one order of magnitude less than Au for similar anneal conditions [41]. Both Al and Cu are considered to be silicon foundry compatible metals although Cu requires better liners and diffusion barriers to prevent diffusion.…”