Kinetics of solid phase epitaxy in thick amorphous Si layers formed by MeV ion implantation

Abstract

The kinetics of solid phase epitaxy (SPE) have been measured in MeV ion-implanted amorphous Si layers up to 5 μm thick. Epitaxial crystallization in these layers occurs at a constant rate throughout the entire film, without loss of interface planarity or competition from random nucleation or twin formation. The activation energy for SPE in thick layers is found to be 2.70 eV, in excellent agreement with the value determined previously in much thinner films. The SPE kinetics are shown not to depend on the implant dose for doses up to 1000 times the threshold for amorphization. The presence of water vapor in the annealing ambient during SPE results in the indiffusion of hydrogen and a concomitant reduction of the SPE growth rate at distances as great as 2 μm from the surface. This effect may have important implications for the development of a microscopic model of the SPE process in silicon.

Self-implantation energy and dose effects on Ge solid-phase epitaxial growth

“…This behavior differs considerably from that of self-amorphized Si, where the SPEG kinetics are independent of implantation conditions [11].…”

“…It is known that H and/or O contamination in the near-surface region during annealing can slow SPEG [11,[33][34][35], though the depth into which such contamination is known to occur (several hundred nm) would imply such an effect would be identical for all a-Ge layer thicknesses used in this work.…”

“…A key difference between Ge and Si is that Ge is known to become highly porous [22][23][24][25][26][27][28][29] at doses above 4 Â 10 15 cm À2 . Such behavior suggests the atomistic nature of the a-Ge phase can be altered with dose or implant energy [30], which may possibly lead to dependence of the SPEG kinetics on self-implantation conditions, in contrast with Si where no such dependence is observed [11]. The goal of this work is to investigate the effects of implantation conditions on Ge SPEG.…”

“…The SPEG process has been studied extensively for Si and is known to be influenced by many variables [10][11][12][13][14][15][16][17][18][19][20][21], though comparatively minimal similar research has been performed for Ge. A key difference between Ge and Si is that Ge is known to become highly porous [22][23][24][25][26][27][28][29] at doses above 4 Â 10 15 cm À2 .…”

TEM analysis of Si thin films prepared by diode laser induced solid phase epitaxy at high temperatures

“…After a certain while the reflectivity drops which is a clear indicator for the solid phase change from amorphous to crystalline silicon and the decrease in refractive index which comes along with it. This continuous drop also suggests that there is no flat epitaxy front reaching the surface since this would lead to a periodical decrease and increase in the reflectivity due to interference effects [10,21]. The related faster rise in the calculated temperature curves is due to the decrease in reflectivity for the heating laser, which leads to an increase in absorbed power.…”