Realization of Abrupt Interfaces in Si/Ge Superlattices by Suppressing Ge Surface Segregation with Submonolayer of Sb

Abstract

Atomic mixing in Si/Ge strained-layer superlattices is investigated by means of SIMS and XPS. The interfacial mixing is attributed to the surface segregation of Ge atoms during MBE growth of Si overlayers. It is demonstrated that the surface segregation is remarkably suppressed by depositing submonolayer Sb atoms on Ge layers prior to Si overgrowth and that Ge layers are confined to within 0.8 nm.

Strain Relaxation of Si/Ge Multilayers Investigated by Transmission Electron Microscopy and High-Resolution X-Ray Diffractometry

“…This result should be related to the diffusion length of Ge in Si, in particular because the presence of strain enhances the interdiffusion process producing an intermixing of about 3-4 ML [34]. In fact, at the growth temperature of our samples, the diffusion length is about 1.1 nm [35,36] which agrees very well with the measured (12 ± 2) nm Six Ge1-x layers thickness. This diffusion length produces a broadening of the nominal pure Ge layer (Tab.…”

Fabrication technology of SiGe hetero-structures and their properties

“…7, the open circles show the XPS intensity of Ge atoms when 0.75 ML of Sb atoms are introduced as suppressors of segregation at the hetero-interface before Si layers are overgrown [35]. It is seen that the XPS intensity follows the exponential decay and that surface segregation is effectively suppressed.…”

“…7, which shows how the surface segregation occurs when Si overlayer is grown on the Ge layers [35]. If Ge atoms sit on the original sites and the site exchange between Ge and impinging Si does not occur, the X-ray photoemission (XPS) intensity of Ge atoms should exponentially decrease with increasing Si overlayer thickness as shown by the broken line.…”

Technique for producing highly planar Si/SiO0.64Ge0.36/Si metal–oxide–semiconductor field effect transistor channels

“…Growth at low temperatures has been reported to kinetically limit Si/SiGe/Si ͑001͒ surface roughening. 3,4 However, such low temperature growth perturbs crystallinity and consequently produces layers of low electrical quality. 5 High quality epitaxial material may be achieved by growing the channel at a low temperature and then annealing out atomic imperfections.…”