Thermal stability of the strained-Si/Si0.7Ge0.3 heterostructure

Abstract

Thermal stability of the strained-Si/Si 0.7 Ge 0.3 heterostructure was investigated by secondary-ion mass spectroscopy, Raman spectroscopy, and atomic force microscopy. Ge atoms diffused out through the strained-Si layer during heat treatment of 1000°C for 1 h. The activation energy of Ge diffusion in strained Si was 3.3 eV, which was lower than the value in unstrained Si ͑4.7-5.3 eV͒. Strain in the strained-Si layer did not change after thermal treatment at 950°C or less for 1 h. Slip lines due to strain relaxation formed at the surface of the strained-Si layer for the samples treated at 950-1000°C for 1 h. For practical application of the strained-Si/Si 0.7 Ge 0.3 heterostructure to electron devices, the maximum thermal budget should be made less than that equivalent to 900°C annealing for 1 h.

HRXRD studies of strain relaxation in ion-implanted strained Si on relaxed Si1−xGex

“…In either case, no strain relaxation was observed. This result is in agreement with previously reported results [3][4][5]. However, postimplantation and anneal, relaxation is observed for this structure.…”

“…The strained overlay is grown to a critical thickness such that the interface is in perfect atomic registry [2]. After thermal processing, the strain energy in these heterostructures decrease and cause strain relaxation by the propagation of threading dislocations and formation of misfits [3][4][5]. Additionally, relaxation can be caused by Ge diffusion into the strained overlay.…”

Misfit strain relaxation and dislocation formation in supercritical strained silicon on virtual substrates

“…Scans were conducted over a 22 h period to maximize the signal-to-noise ratio, but the technique still only yields sufficient x-ray intensity for layers thicker than 15 nm. Annealing of strained silicon layers is known to induce Ge diffusion from the virtual substrate, 6 which will reduce its thickness. In order to determine a suitable range of temperatures over which to conduct annealings, secondary ion mass spectroscopy ͑SIMS͒ performed a 32 nm strained silicon layer in the as-grown state and after it had been subjected to annealings for 1 h at 750, 850, and 950°C ͑Fig.…”

Alloying of self-organized semiconductor 3D islands

“…either through migration of vacancies or through a process involving the formation of Ge interstitials and the substitution of Ge with Si [79]. In general, the latter mechanism is thought to dominate the intermixing issue, with fairly high potential barriers of 4-5 eV [80]. For the temperatures at which Ge/Si QDs are usually grown (between 500 and 700 C) such processes should therefore be considered as practically absent.…”