Solid phase epitaxy (SPE)[1] involves the deposition of an amorphous layer followed by an annealing stage. An a-Si layer was deposited on a p-Al mediator film[2] (Fig. 2.2a), then thermally annealed for about ten hours at temperatures of \(450 - 530^\circ \textrm{C}\). The a-Si was observed to have diffused through the p-Al layer toward the buried Al/Si interface. In a similar experiment[3], with a shorter annealing stage of four hours at \(400^\circ \textrm{C}\) then thirty minutes at \(500^\circ \textrm{C}\), the Si reportedly diffused through the p-Al film. However, no information regarding the quality of the buried Si thin film was published. In original experiments[4], c-Al(111) was shown to grow initially, followed by the subsequent growth of c-Si(111) at the buried c-Si/c-Al interface.
Figure 2-2. Solid Phase Epitaxy (SPE) a) An a-Si layer is deposited atop a p-Al film. b) After annealing, the product of SPE is a substrate/p-c diffusor/p-mediator sandwich. The resulting structure has a relatively poor quality buried Si film, and the resulting p-Al/Si interface is jagged. |
Other SPE experiments have made use of a wide variety of mediator and diffusing materials. SMME is anticipated to be useful with a similar array of materials and better-quality crystalline films.
References
- , “Topics in Solid Phase Epitaxy: Strain, Structure and Geometry”, Materials Science and Engineering, vol. R16, no. 1, 1996.
- , “Solid Phase Epitaxial Growth of Si Through Al Film”, Proceedings of the Symposium on Thin Film Phenomena Interfaces and Interactions, vol. 78. p. 293, 1978.
- , “Efficient Si solar cells by low‐temperature solid‐phase epitaxy”, Appl. Phys. Lett., vol. 39, 1981.
- , “Epitaxial Growth of Si(111) at Buried Interfaces Using Solid-Metal Mediated Molecular Beam Epitaxy”, in 1996 MRS Spring Meeting, San Francisco, CA, 1996.