Search

Epitaxial growth of Ni(Al)Si0.7Ge0.3 on relaxed Si0.7Ge0.3/Si(100) substrates was achieved via an Al interlayer mediated epitaxy. After annealing, most of the Al atoms from the original 3 nm interlayer diffused toward the surface but the remaining Al atoms in the epitaxial monogermanosilicide distributed uniformly, independent of the annealing temperatures. The incorporation of Al increases the transition temperature from the Ni-rich germanosilicide phase to the monogermanosilicide phase. The reduced Ni diffusion, the increased lattice constant due to substitutional Al, and the increased thermal expansion of monogermanosilicide are assumed to be the main mechanisms enabling the epitaxial growth of the quaternary silicide. [ABSTRACT FROM AUTHOR]

In this letter we present a method to increase the efficiency of SiGe layer relaxation by He+ ion implantation and annealing. Preferential nucleation of He platelets along a δ-impurity layer grown in the Si substrate below the SiGe layer results in planar localization and homogenization of dislocation loop sources inducing a more uniform distribution of misfit dislocations. We demonstrate this for a thin Si:C layer grown by reduced pressure chemical vapor deposition. The optimization of the conditions for efficient relaxation and layer quality is studied with respect to the position of the Si:C layer and the process parameters. Relaxation degrees up to 85% are obtained for Si0.77Ge0.23 layers. [ABSTRACT FROM AUTHOR]

Uniaxially strained (011)Si is attractive for high performance p-channel metal oxide semiconductor field effect transistor devices due to the predicted high hole mobilities. Here, we demonstrate the realization of purely uniaxially relaxed (011) SiGe virtual substrates by He+ ion implantation and thermal annealing. Perfect uniaxial relaxation is evidenced by precise ion channeling angular yield scan measurements and plan view transmission electron microscopy as predicted theoretically on the basis of the layer symmetry dependent dislocation dynamics. Strikingly, misfit dislocations propagate exclusively along the [011] direction in the (011) oriented crystal and, in contrast to (100)Si, no crosshatch is formed. We describe dislocation formation and propagation inducing strain relaxation of (011)SiGe and enlighten the differences to (100) oriented SiGe on Si. [ABSTRACT FROM AUTHOR]

Hydrogen ion implantation is conventionally used to initiate the transfer of Si thin layers onto Si wafers coated with thermal oxide. In this work, we studied the feasibility of using plasma hydrogenation to replace high dose H implantation for layer transfer. Boron ion implantation was used to introduce H-trapping centers into Si wafers to illustrate the idea. Instead of the widely recognized interactions between boron and hydrogen atoms, this study showed that lattice damage, i.e., dangling bonds, traps H atoms and can lead to surface blistering during hydrogenation or upon postannealing at higher temperature. The B implantation and subsequent processes control the uniformity of H trapping and the trap depths. While the trap centers were introduced by B implantation in this study, there are many other means to do the same without implantation. Our results suggest an innovative way to achieve high quality transfer of Si layers without H implantation at high energies and high doses. [ABSTRACT FROM AUTHOR]

The use of plasma hydrogenation for relaxed SiGe layer transfer is demonstrated. It is found that the interface of a strain-relaxed SiGe/Si heterostructure is effective in trapping H during plasma hydrogenation. Long microcracks observed at the interface due to the trapping of indiffused H indicate the distinct possibility of transferring the overlayer using the ion-cutting technique. Our results suggest that interfacial defects induced by the He implantation relaxation process trap the indiffusing H atoms and lead to interfacial cracks during hydrogenation or upon postannealing at higher temperatures. It is further noted that trapping of H at the interface is possible only in strain-relaxed structures. Without strain relaxation, H atoms introduced by plasma hydrogenation get trapped just below the sample surface and form a band of shallow platelets. Without the need for high-dose high-energy ion implantation, our results suggest an effective way for high-quality strain-relaxed SiGe layer transfer. The technique has potential for application in the fabrication of SiGe-on-insulator strained Si epitaxial layer and related structures. [ABSTRACT FROM AUTHOR]

An approach for the controlled formation of thin strained silicon layers based on strain transfer in an epitaxial Si/SiGe/Si(100) heterostructure during the relaxation of the SiGe layer is established. He+ ion implantation and annealing is employed to initiate the relaxation process. The strain transfer between the two epilayers is explained as an inverse strain relaxation which we modeled in terms of the propagation of the dislocations through the layers. Effcient strain buildup in the Si top layer strongly depends on the Si top layer thickness and on the relaxation degree of the SiGe buffer. 100% strain transfer was observed up to a critical thickness of the strained silicon layer of 8 nm for a 150 nm relaxed Si0.74Ge0.26 buffer. [ABSTRACT FROM AUTHOR]