| AVS 54th International Symposium | |
| Electronic Materials and Processing | Wednesday Sessions |
| Session EM-WeM |
| Session: | Contacts, Interfaces and Defects in Semiconductors |
| Presenter: | C.Y. Lu, University of Washington |
| Authors: | C.Y. Lu, University of Washington E.N. Yitamben, University of Washington T.C. Lovejoy, University of Washington K.M. Beck, Pacific Northwest National Laboratory A.G. Joly, Pacific Northwest National Laboratory M.A. Olmstead, University of Washington F.S. Ohuchi, University of Washington |
| Correspondent: | Click to Email |
The strong change in optical reflectivity during the amorphous-crystalline phase transition in ternary chalcogenides is the basis of re-writeable compact disc and digital video disk technology. The binary, group-III-chalcogenide semiconductor, In2Se3 has recently been proposed as a resistance-based phase-change random access memory (PRAM) material due to its large (105) resistance change between the crystalline and amorphous phases.1 The intrinsic vacancies and structural variability characterizing crystalline In2Se3 likely play an important role in controlling phase-change characteristics. We have investigated growth of amorphous and epitaxial In2Se3 films on Si(111), as well as the crystallization of amorphous In2Se3 films through resistive annealing using a combination of scanning tunneling microscopy, photoemission spectroscopy, and X-ray diffraction. Amorphization of crystalline In2Se3 films by laser annealing was studied using photo electron emission microscopy. Despite the 7.3% lattice mismatch, we are able to grow laminar, epitaxial films of γ- In2Se3 (0001) up to at least 3 nm in thickness that exhibit a surface reconstruction associated with the ordered vacancy structure; we attribute this ability to grow laminar films to the flexibility provided by the intrinsic vacancy structure. A minimum thickness of 2 bilayers (0.64 nm) is required to undergo the phase change and a minimum thickness of 3 bilayers (0.96 nm) is required for the ordered-vacancy reconstruction characteristic of the epitaxially grown material during phase change. Annealing room-temperature-deposited films can transform amorphous In2Se3 to be highly textured γ- In2Se3 with the (0001) plane parallel the substrate surface. A buffer layer of epitaxial In2Se3 before deposition of the amorphous film lowers the crystallization temperature and improves the uniformity of the crystalline In2Se3 phase. This work was supported by NSF grant DMR 0605601. TCL acknowledges support from NSF/NCI IGERT DGE-0504573. Some of the research was pursued at the Advanced Light Source, which is supported by the DOE under contract DE-AC02-05CH11231. KMB acknowledges the support from U.S. Department of Energy by Battelle Corporation.
1 H. Lee, D-H. Kang, and L. Tran, Mat. Sci. Eng. B 119 (2004) 196.