Hostname: page-component-6d856f89d9-mhpxw Total loading time: 0 Render date: 2024-07-16T06:42:09.602Z Has data issue: false hasContentIssue false
  • English
  • Français

Solidification of highly undercooled liquid silicon produced by pulsed laser melting of ion-implanted amorphous silicon: Time-resolved and microstructural studies

Published online by Cambridge University Press:  31 January 2011

D. H. Lowndes ,
S. J. Pennycook ,
G. E. Jellison Jr. ,
S. P. Withrow  and
D. N. Mashburn
D. H. Lowndes
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
S. J. Pennycook
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
G. E. Jellison Jr.
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
S. P. Withrow
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
D. N. Mashburn
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
Get access

Abstract

Nanosecond resolution time-resolved visible (632.8 nm) and infrared (1152 nm) reflectivity measurements, together with structural and Z-contrast transmission electron microscope (TEM) imaging, have been used to study pulsed laser melting and subsequent solidification of thick (190–410 nm) amorphous (a) Si layers produced by ion implantation. Melting was initiated using a KrF (248 nm) excimer laser of relatively long [45 ns full width half maximum (FWHM)] pulse duration; the microstructural and time-resolved measurements cover the entire energy density (E1) range from the onset of melting (at ∼ 0.12J/cm2) up to the onset of epitaxial regrowth (at ∼ 1.1 J/cm2). At low E1 the infrared reflectivity measurements were used to determine the time of formation, the velocity, and the final depth of “explosively” propagating buried liquid layers in 410 nm thick a-Si specimens that had been uniformly implanted with Si, Ge, or Cu over their upper ∼ 300 nm. Measured velocities lie in the 8–14 m/s range, with generally higher velocities obtained for the Ge- and Cu-implanted “a-Si alloys.” The velocity measurements result in an upper limit of 17 (± 3) K on the undercooling versus velocity relationship for an undercooled solidfying liquid-crystalline Si interface. The Z-contrast scanning TEM measurements of the final buried layer depth were in excellent agreement with the optical measurements. The TEM study also shows that the “fine-grained polycrystalline Si” region produced by explosive crystallization of a-Si actually contains large numbers of disk-shaped Si flakes that can be seen only in plan view. These Si flakes have highly amorphous centers and laterally increasing crystallinity; they apparently grow primarily in the lateral direction. Flakes having this structure were found both at the surface, at low laser E1, and also deep beneath the surface, throughout the “fine-grained poly-Si” region formed by explosive crystallization, at higher E1. Our conclusion that this region is partially amorphous (the centers of flakes) differs from earlier results. The combined structural and optical measurements suggest that Si flakes nucleate at the undercooled liquid-amorphous interface and are the crystallization events that initiate explosive crystallization. Time-resolved reflectivity measurements reveal that the surface melt duration of the 410 nm thick a-Si specimens increases rapidly for 0.3E1 <0.6 J/cm2, but then remains nearly constant for E1 up to ∼ 1.0 J/cm2. For 0.3 < E1 < 0.6 J/cm2 the reflectivity exhibits a slowly decaying behavior as the near-surface pool of liquid Si fills up with growing large grains of Si. For higher E1, a flat-topped reflectivity signal is obtained and the microstructural and optical studies together show that the principal process occurring is increasingly deep melting followed by more uniform regrowth of large grains back to the surface. However, cross-section TEM shows that a thin layer of fine-grained poly-Si still is formed deep beneath the surface for E1<0.9 J/cm2, implying that explosive crystallization occurs (probably early in the laser pulse) even at these high E1 values. The onset of epitaxial regrowth at E1 = 1.1 J/cm2 is marked by a slight decrease in surface melt duration.

Type
Articles
Information
Journal of Materials Research , Volume 2 , Issue 5 , October 1987 , pp. 648 - 680
Copyright
Copyright © Materials Research Society 1987

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1Wood, R. F. and Jellison, G. E. Jr., in Semiconductors and Semimetals, V. 23: Pulsed Laser Processing of Semiconductors, edited by Wood, R. F., White, C. W., and Young, R. T. (Academic, New York, 1984), Chap. 4.Google Scholar
2White, C. W., in Ref. 1, Chap. 2.Google Scholar
3Cullis, A. G., Webber, H. C., Poate, J. M., and Simons, A. L., Appl. Phys. Lett. 36, 320 (1980).CrossRefGoogle Scholar
4Baeri, P., Foti, G., Poate, J. M., Campisano, S. U., and Cullis, A. G., Appl. Phys. Lett. 38, 800 (1981).CrossRefGoogle Scholar
5Wood, R. F. and Young, F. W. Jr., in Ref. 1, Chap. 5.Google Scholar
6Lowndes, D. H., Wood, R. F., and Narayan, J., Phys. Rev. Lett. 52, 561 (1984).CrossRefGoogle Scholar
7Lowndes, D. H., Jellison, G. E. Jr., Wood, R. F., and Carpenter, R., in the Proceedings of the 17th International Conference on Physics of Semiconductors (Springer, Berlin, 1985), p. 1497.CrossRefGoogle Scholar
8Lowndes, D. H., Jellison, G. E. Jr., Wood, R. F., Pennycook, S. J., and Carpenter, R. F., Mater. Res. Soc. Symp. Proc. 35, 101 (1985); Note: The 190 nm a layer thickness mentioned in the capition to Fig. 4 of this reference (and in its discussion in the text) is incorrect; the correct thickness was 440 nm.CrossRefGoogle Scholar
9Campisano, S. U., Jacobson, D. C., Poate, J. M., Cullis, A. G., and Chew, N. G., Appl. Phys. Lett. 45, 1217 (1984).CrossRefGoogle Scholar
10Campisano, S. U., Jacobson, D. C., Poate, J. M., Cullis, A. G., and Chew, N. G., Appl. Phys. Lett. 46, 846 (1985).CrossRefGoogle Scholar
11Narayan, J., J. Vac. Sci. Technol. A 4, 61 (1986).CrossRefGoogle Scholar
12Peercy, P. S., Poate, J. M., Thompson, M. O., and Tsao, J. T., Appl. Phys. Lett. 48, 1651 (1986).CrossRefGoogle Scholar
13Peercy, P. S., Thompson, M. O., Tsao, J. Y., and Poate, J. M., Mater. Res. Soc. Symp. Proc. 51, 125 (1986); See also M. O. Thompson, J. W. Mayer, A. G. Cullis, H. C. Webber, N. G. Chew, J. M. Poate, and D. C. Jacobson, Phys. Rev. Lett. 50, 896 (1983).CrossRefGoogle Scholar
14Wood, R. F., Lowndes, D. H., and Narayan, J., Appl. Phys. Lett. 44, 770 (1984).CrossRefGoogle Scholar
15Narayan, J. and White, C. W., Appl. Phys. Lett. 44, 35 (1984).CrossRefGoogle Scholar
16Thompson, M. O., Galvin, G. J., Mayer, J. W., Peercy, P. S., Poate, J. M., Jacobson, D. C., Cullis, A. G., and Chew, N. G., Phys. Rev. Lett. 52, 2360 (1984).CrossRefGoogle Scholar
17Gore, G., Philos. Mag. 9, 73 (1855).CrossRefGoogle Scholar
18Gilmer, G. H. and Leamy, H. J., in Laser and Electron Beam Processing of Materials, edited by White, C. W. and Peercy, P. S. (Academic, New York, 1980), p. 227.CrossRefGoogle Scholar
19Leamy, H. J., Brown, W. L., Celler, G. K., Foti, G., Gilmer, G. H., and Fan, J. C. C., Appl. Phys. Lett. 38, 137 (1981).CrossRefGoogle Scholar
20Thompson, M. O., Bucksbaum, P. H., and Bokor, J., Mater. Res. Soc. Symp. Proc. 35, 181 (1985).CrossRefGoogle Scholar
21Larson, B. C., Tischler, J. Z., and Mills, D. M., J. Mater. Res. 1, 144 (1986).CrossRefGoogle Scholar
22Galvin, G. J., Mayer, J. W., and Peercy, P. S., Appl. Phys. Lett. 46, 644 (1985).CrossRefGoogle Scholar
23Tsao, J. Y. and Peercy, P. S., Phys. Rev. Lett. 58, 2782 (1987).CrossRefGoogle Scholar
24Thompson, M. O., (private communication).Google Scholar
25Galvin, G. J., Thompson, M. O., Mayer, J. W., Hammond, R. B., Paulter, N., and Peercy, P. S., Phys. Rev. Lett. 48, 33 (1982).CrossRefGoogle Scholar
26Lowndes, D. H., Jellison, G. E. Jr., Pennycook, S. J., Withrow, S. P., Mashburn, D. N., and Wood, R. F., Mater. Res. Soc. Symp. Proc. 51, 131 (1986).CrossRefGoogle Scholar
27Lowndes, D. H., Jellison, G. E. Jr., Pennycook, S. J., Withrow, S. P., and Mashburn, D. N., Appl. Phys. Lett. 48, 1389 (1986).CrossRefGoogle Scholar
28Wood, R. F. and Geist, G. A, Phys. Rev. Lett. 57, 873 (1986).CrossRefGoogle Scholar
29Pennycook, S. J. and Narayan, J., Appl. Phys. Lett. 45, 385 (1984); S. J. Pennycook, S. D. Berger, and R. J. Culbertson, J. Microsc. 144, 229 (1986).CrossRefGoogle Scholar
30Peercy, P. S. and Thompson, M. O., Mater. Res. Soc. Symp. Proc. 35, 53 (1985).CrossRefGoogle Scholar
31Lowndes, D. H., Jellison, G. E. Jr., and Wood, R. F., Phys. Rev. B 26, 6747 (1982).CrossRefGoogle Scholar
32Webber, H. C., Cullis, A. G., and Chew, N. G., Appl. Phys. Lett. 43, 669 (1983).CrossRefGoogle Scholar
33See Wood, R. F. and Geist, G. A., Phys. Rev. B 34, 2606 (1986).CrossRefGoogle Scholar
34Donovan, E. P., Spaepen, F., Turnbull, D., Poate, J. M., and Jacobson, D. C., Appl. Phys. Lett. 42, 698 (1983).CrossRefGoogle Scholar
35See Donovan, E. P., Spaepen, F., Turnbull, D., Poate, J. M., and Jacobson, D. C., J. Appl. Phys. 57, 1795 (1985), and references therein to earlier work.CrossRefGoogle Scholar
36Glassbrenner, C. J. and Slack, G. A., Phys. Rev. 134, A1058 (1964).CrossRefGoogle Scholar
37Papa, T., Scudieri, F., Marinelli, M., Zammit, U., and Cembali, G. (private communication).Google Scholar
38Goldsmit, H. J., Kaila, M. M., and Paul, G. L., Phys. Status Solidi A 76, K31 (1983).Google Scholar
39Jellison, G. E. Jr., and Lowndes, D. H., Appl. Phys. Lett. 41, 594 (1982).CrossRefGoogle Scholar
40Jellison, G. E. Jr., and Burke, H. H., Appl. Phys. Lett. 60, 841 (1986).Google Scholar
41Bruggeman, D. A. G., Ann. Phys. (5 Folge) 24, 636 (1935).CrossRefGoogle Scholar
42Devaud, G. and Turnbull, D., Appl. Phys. Lett. 46, 844 (1985).CrossRefGoogle Scholar