Pulsed Beam Annealing Research Articles

Coincidence of the thermal melting points of crystalline and amorphous Si and coincidence of thresholds for pulsed beam annealing of crystalline and amorphous Si and GaAs

In spite of the excess enthalpy of amorphism, neither the normal thermal melting point of Si nor the threshold absorbed energy density for pulsed electron and pulsed laser beam annealing of Si and GaAs is significantly dependent on whether the sample is initially amorphous or crystalline. However, the duration of the period of high optical reflectivity and the magnitude of atomic diffusion during the annealing event are much enhanced near threshold if the sample is initially amorphous. Here these facts are explained in terms of conventional theory of covalent bonding and of the normal thermal melting process and in terms of the “Plasma Annealing” theory of pulsed beam annealing.

Experimental tests for Boson condensation and superconductivity in semiconductors during pulsed beam annealing: J. A. Van Vechten. Solid State Communications39, 1285 (1981)

Experimental tests for Boson condensation and superconductivity in semiconductors during pulsed beam annealing: J. A. Van Vechten. Solid State Communications39, 1285 (1981)

Experimental tests for boson condensation and superconductivity in semiconductors during pulsed beam annealing

Van Vechten and Compaan and, independently, Nagy and Noga have proposed that the high reflectivity state observed in pulsed laser/electron/ion beam annealing of Si and other semiconductors results when the electron-hole plasma created by the initial absorption of the ionizing radiation undergoes a boson condensation. The condensed state is described in the same form as the BCS superconductor and has many of the properties of the superconducting state. Lattice temperatures for the material during this phase have beeb measured by Raman scattering to lie in the range from 500 to 1000 K. At this writing no magnetic experiment has been completed to test this proposition further. In addition to the practical problems associated with such a test, there are theoretical questions such as whether or not the bipolar plasma ought to be able to expel a magnetic field within the 100 ns or so that it persists in the proposed boson condensed phase. If not, it does not exhibit perfect diamagnetism and the Meissner effect. An experiment is proposed that is argued to be both easy to perform and to offer a conclusive demonstration of boson condensation. The proposed experiment involves observation of the single plasmon mode by diffraction or from the appearance of linear ripples left on the solid surface and the rotation of this pattern. Preliminary observations seem to confirm the condensation.

Selected Application of Electron Beams in Solid State Materials and Devies Technology

Experimental work on electron beam annealing of implanted or diffused semiconductor layers is reviewed. In the pulsed beam annealing technique, the top layer of the semiconductor melts and regrows epitaxially. All dopant atoms are frozen in electrically active state during this process. The point defects and clusters caused by radiation damage are completely annealed out. The bulk of the material remains unaffected as its temperature does not rise by more than a few degrees. In the CW electron beam annealing, the layer does not melt but due to sharp temperature gradient and high temperature of the layer, the growth of solid phase epitaxial layer is induced. However, a part of the dopant atoms may remain electrically inactive in this process of annealing. The pulsed beam annealing has also been used for growing high quality single crystal layers of germanium on silicon substrate. Recently, a new technology has been developed to grow silicon single crystal layers on amorphous substrates. Recent advances in the method of determination of lifetime using electron beams are also discussed.