Method and system for forming SbSI thin films

Details Method and system for forming SbSI thin films Method and system for forming SbSI thin films

2000-08-21

2001-07-24

Bueker, Richard (Department: 1763)

Coating apparatus

Gas or vapor deposition

With treating means

C118S726000

Reexamination Certificate

active

06264750

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
This invention relates to growing thin films and more specifically to a method and system for forming SbSI thin films.
BACKGROUND OF THE INVENTION
SbSI (ferroelectric antimony sulfo-iodide) in its crystal form exhibits the Curie temperature around room temperature (the Curie temperature is the temperature above which a material loses its ferroelectricity). SbSI simultaneously exhibits both semiconductor and ferroelectric properties. Although the crystal form of SbSI has been studied, SbSI thin films have not been examined as extensively. Attempts have been made to form thin films of SbSI by e-beam evaporation, flash evaporation, and thermal evaporation. These techniques have produced thin films but these thin films are nonstoichiometric and amorphous. Thus, these films fail to fully exhibit the physical properties of SbSI.
Attempts have been made to form thin films of SbSI through the use of physical vapor transport (PVT) onto a substrate, typically a Pt/Ta/SiO
2
/Si substrate (platinum/tantalum/silicon dioxide/silicon substrate). While this technique can form thin films of SbSI, the crystal structure tends to be random in nature and thus does not fully exhibit all the desirable properties of SbSI. What is needed is a method and system for growing high quality SbSI thin films.
SUMMARY OF THE INVENTION
Accordingly, it may be appreciated that a need has arisen for a method and system for forming SbSI thin films. In accordance with the teaching of the present invention, a method and system to form SbSI thin films are provided that substantially eliminates or reduces the disadvantages of previous methods.
In one embodiment, a method for forming SbSI thin films is provided. In the first step of the method, a substrate is provided. Next a buffer layer is formed on the substrate. Then, a SbSI source is provided. The SbSI source and buffer layer with a substrate are placed in an evacuated ampoule. The ampoule is heated in a two-zone oven. This causes the SbSI source to form a vapor which reacts with the buffer layer to form a thin film of SbSI.
In another embodiment, a system for forming thin film of SbSI is provided. The system comprises an ampoule which contains an SbSI source inside at one location and a substrate with a buffer layer inside at a second location. The ampoule is placed inside a two-zone furnace, holding the SbSI source at one temperature and the buffer layer and substrate at a second, lower temperature. The furnace causes the SbSI source to vaporize and the vapor reacts with the buffer layer to form a SbSI film on the substrate.
The present invention provides various technical advantages over current methods. For example, high quality thin films of SbSI can be formed. Also, by simply changing the annealing conditions of the buffer layer, the alignment of the crystal structure of SbSI can be changed, changing physical characteristics. Additionally, a thin film of SbSI is formed with a Curie point around room temperature and a high dielectric constant at that Curie point. Other technical advantages may be readily apparent to one skilled in the art from the following figures, descriptions and claims.


REFERENCES:
N. Solayappan, et al.; J. Mater. Res., 12(3), pp. 825-832,1997.
R. Nitsche and W.J. Merz, “Photoconduction in Ternary V-VI-VII Compounds,” J. Phys. Chem. Solids Pergamon Press, vol. 13, pp. 154-155 (1960).
E. Fatuzzo, G. Harbeke, W.J. Merz, R. Nitsche, H. Roetschi, and W. Ruppel, “Ferroelectricity in SbSI,” Phys. Rev., vol. 127, No. 6, pp. 2036-2037 (Sep. 15, 1962).
R. Nitsche, H. Roetschi, and P. Wild, “New Ferroelectric V•VI•VII Compound of the SbSI Type,” Appl. Phys. Lett. vol. 4, No. 12, pp. 210-211 (Jun. 15, 1964).
L.A. Zadorozhnaya, V.A. Lyachovitskaya, E.I. Givargizov, and L.M. Belyaev, “Vapour Growth of SbSI on a Seed,” J. Cryst. Growth 41, pp. 61-66 (1977).
K. Toyoda, “Electrical Properties of SbSI Crystals in the Vicinity of the Ferroelectric Curie Point,” Ferroeletrics vol. 69, pp. 201-215 (1986).
E.I. Gerzanich, L.A. Lyakhovitskaya, V.M. Fridkin, and B.A. Popovkin, “Current Topics in Materials Science,” edited by E. Kaldis (North-Holland Publishing Company) pp. 141-155, 1982.
J. Li, D. Viehland, A.S. Bhalla, and L.E. Cross, “Pyro-optic Studies for Infrared Imaging,” J. Appl. Phys., vol. 71 (5), pp. 2106-2112 (1992).
L.E. Cross, A. Bhalla, F. Ainger, and D. Damjanovic, U.S. Patent No. 4994672, “Pyro-optic Detector and Imager,” Issued Feb. 19, 1991, http://www.patents.ibm.com/details?&pn=US04994672.
M. Yoshida, K. Yamanaka, and Y. Hamakawa, “Semiconducting and Dielectric Properties of C-Axis Oriented SbSI Thin Film,” Jpn. J. Appl. Phys. vol. 12, No. 11, pp. 1699-1705 (Nov. 1973).
A. Mansingh and T. Sudarsena Rao, “Growth and Characterization of Flash-evaporated Ferroelectric antimony Sulpholodide Thin Films,” J. Appl. Phys. 58 (9), pp. 3530-3535 (1985).
P.K. Ghosh, A.S. Bhalla, L.E. Cross, “Preparation and Electrical Properties of Thin Films of Antimony Sulphur Iodide (SbSI),” Ferroelectrics vol. 51, pp. 29-33 (1983).
S. Narayanan and R. K. Pandey, “Physical Vapor Deposition of Antimony Supho-Iodide (SbSI Thin Films and Their Properties,” in Proc. 9th Int. Symp. Appln. of Ferroelectrics (University Park, PA, 1994), pp. 309-311 (also see dissertation, “Growth and Evaluation of Ferroelectric SbSI Thin Films for Thermal Imaging Applications,” by Narayanan Solayappan, Texas A&M University, May 1996).
V.A. Aleshin and B.A. Popovkin, “Chemical Transport of SbSI and BiSI by Iodine and Sulphur,” Neorganicheskie Materialy, vol. 26, No. 7, pp. 1391-1394, Jul. 1990.
A.I. Pankrashov, L.A. Zadorozhnaya, and E.I. Givargizov, “Oriented Crystallization of SbSI on Amorphous Substrates by Artificial Epitaxy,” Sov. Phys. Crystallogr. vol. 32 (3), pp. 429-431 (May-Jun. 1987).
Bum Ki Moon and Hiroshi Ishiwara, “Roles of Buffer Layers in Epitaxial Growth of SrTiO3Films on Silicon Substrates,” Jpn. J. Appl. Phys. vol. 33, pp. 1472-1477 (1994).
Joon Sung Lee, Chang Jung Kim, Dae Sung Moon, Chaun Gi Choi, Jae Myung Kim, and Kwangsoo No, “Effects of Seeding Layer on Perovskite Transformation, Microstructure and Transmittance of Sol-Gel-Processed Lanthanum-Modified Lead Zirconate Titanate Films,” Jpn. J. Appl. Phys. vol. 33, pp. 260-265, Part 1, No. 1A (Jan. 1994).
P. Arun and A.G. Vedeshawar, “Phase Modification by Instantaneous Heat Treatment of Sb2S3Films and Their Potential for Photothermal Optical Recording,” J. Appl. Phys. 79 (8), pp. 4029-4036 (Apr. 15, 1996).

Affiliated with

Also associated with

Rating

Method and system for forming SbSI thin films does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method and system for forming SbSI thin films, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for forming SbSI thin films will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2540299