Growth and properties of strained Si_1-x-yGe_xC _y layers

authored by

S. C. Jain, H. J. Osten, B. Dietrich, H. Rücker

Abstract

Advances made in the growth and properties of CSi and CSiGe pseudomorphic strained layers are reviewed. The solubility of C in Si is small (3.5*10¹⁷ atoms/cm³ near the melting point). However, high-quality strained layers of the alloys with considerably larger C concentrations have been grown using MBE, CVD and solid-phase epitaxy methods. A careful control of the growth rate and temperature is necessary to avoid formation of silicon carbide. In high-quality layers, most of the C atoms occupy lattice positions of the Si or SiGe host crystals and a substitutional alloy is formed although the equilibrium volume of C atoms is only 30% of that of Si. The formation and stability of alloys of atoms with large differences in size is a topic of fundamental interest. Experimental and theoretical investigations have focused on the microscopic structure of substitutional Si _1-x-yGe_xC_y alloys. C compensates the compressive strain produced by Ge in the pseudomorphic layers grown on a Si substrate. From Raman studies of the microscopic strain in substitutional Si_1-x-yGe_xC_y alloys it has been concluded that Si-Si bonds experience a considerable local deformation even in strain-compensated alloys. The pair interaction of substitutional C atoms in an Si lattice and the possibility of forming ordered alloys have been studied theoretically. It has been found that the interaction of pairs of substitutional C atoms is attractive for special atomic configurations. Information available on electronic properties is rather meagre. Recent theoretical work shows that the bandgap of the alloy should decrease with C concentration. Experiments to confirm this have not yet been performed. Using strain-compensated alloys it is possible to grow symmetrically strained superlattices without the need of growing buffer layers. Si_1-x-yGe_xC_y strained layers are likely to be very useful for passive applications such as buffer layers. Considerably more work is required to determine their utility for active device applications.

Organisation(s)

Institute of Electronic Materials and Devices

External Organisation(s)

University of Oxford

Type

Review article

Journal

Semiconductor Science and Technology

Volume

10

Pages

1289-1302

No. of pages

14

ISSN

0268-1242

Publication date

1995

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Condensed Matter Physics, Electrical and Electronic Engineering, Materials Chemistry

Electronic version(s)

https://doi.org/10.1088/0268-1242/10/10/001 (Access: Closed)