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Title: Thermodynamics and kinetics of crystallization of amorphous silicon and germanium produced by ion implantation

Abstract

Amorphous silicon and germanium (a-Si and a-Ge) layers were produced on single crystal substrates by high-energy (less than or equal to3 MeV) implantation of argon and xenon ions. The dose, dose rate, and temperature dependence of the Ar/sup +/ ion implantation process was investigated. To create an amorphous layer, 2 X 10/sup 14/Ar/sup +//cm/sup 2/ at 1.7 MeV for silicon and 2 X 10/sup 13/ Ar/sup +//cm/sup 2/ at 1.6 MeV for germanium were found sufficient to create an amorphous layer on liquid nitrogen cooled substrates at a fluence of 0.12 ..mu..A/cm/sup 2/, as determined by Rutherford backscattering spectroscopy (RBS) of 1.0 MeV protons. Differential scanning calorimetry (DSC) and RBS were used to investigate the crystallization behavior of a-Si and a-Ge, and to obtain the enthalpies of crystallization, ..delta..H/sub ac/. Amorphous germanium was found to relax to an amorphous state of lower energy with an enthalpy of relaxation of 1.43 kcal/mole. Relaxed a-Ge crystallized with ..delta..H/sub ac/ = 2.79 +/- 0.17 kcal/mole. The epitaxial growth velocity of (100) substrates was determined to be V = 4.17 X 10/sup 17/ exp(-2.17 eV kT)A/sec, with an average Ar concentration of 2 X 10/sup 18/ cm/sup -3/. Layers of amorphous silicon were producedmore » under a variety of implantation conditions at 77K. Relaxation to a lower energy amorphous state was not found to occur. The value of ..delta..H/sub ac/ was found to be 2.86 +/- 0.23 kcal/mole, with crystallization kinetics that were shown to be impurity concentration dependent, and in good agreement with literature values. A Gibbs free energy diagram for a-Si was derived and used to estimate the melting temperature of a-Si to be 1420 K.« less

Authors:
Publication Date:
Research Org.:
Harvard Univ., Cambridge, MA (USA)
OSTI Identifier:
6899275
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; GERMANIUM; CRYSTALLIZATION; THERMODYNAMIC PROPERTIES; SILICON; AMORPHOUS STATE; ARGON IONS; CALORIMETRY; ION IMPLANTATION; MONOCRYSTALS; PHYSICAL RADIATION EFFECTS; XENON IONS; CHARGED PARTICLES; CRYSTALS; ELEMENTS; IONS; METALS; PHASE TRANSFORMATIONS; PHYSICAL PROPERTIES; RADIATION EFFECTS; SEMIMETALS; 360603* - Materials- Properties; 360605 - Materials- Radiation Effects

Citation Formats

Donovan, E P. Thermodynamics and kinetics of crystallization of amorphous silicon and germanium produced by ion implantation. United States: N. p., 1982. Web.
Donovan, E P. Thermodynamics and kinetics of crystallization of amorphous silicon and germanium produced by ion implantation. United States.
Donovan, E P. Fri . "Thermodynamics and kinetics of crystallization of amorphous silicon and germanium produced by ion implantation". United States.
@article{osti_6899275,
title = {Thermodynamics and kinetics of crystallization of amorphous silicon and germanium produced by ion implantation},
author = {Donovan, E P},
abstractNote = {Amorphous silicon and germanium (a-Si and a-Ge) layers were produced on single crystal substrates by high-energy (less than or equal to3 MeV) implantation of argon and xenon ions. The dose, dose rate, and temperature dependence of the Ar/sup +/ ion implantation process was investigated. To create an amorphous layer, 2 X 10/sup 14/Ar/sup +//cm/sup 2/ at 1.7 MeV for silicon and 2 X 10/sup 13/ Ar/sup +//cm/sup 2/ at 1.6 MeV for germanium were found sufficient to create an amorphous layer on liquid nitrogen cooled substrates at a fluence of 0.12 ..mu..A/cm/sup 2/, as determined by Rutherford backscattering spectroscopy (RBS) of 1.0 MeV protons. Differential scanning calorimetry (DSC) and RBS were used to investigate the crystallization behavior of a-Si and a-Ge, and to obtain the enthalpies of crystallization, ..delta..H/sub ac/. Amorphous germanium was found to relax to an amorphous state of lower energy with an enthalpy of relaxation of 1.43 kcal/mole. Relaxed a-Ge crystallized with ..delta..H/sub ac/ = 2.79 +/- 0.17 kcal/mole. The epitaxial growth velocity of (100) substrates was determined to be V = 4.17 X 10/sup 17/ exp(-2.17 eV kT)A/sec, with an average Ar concentration of 2 X 10/sup 18/ cm/sup -3/. Layers of amorphous silicon were produced under a variety of implantation conditions at 77K. Relaxation to a lower energy amorphous state was not found to occur. The value of ..delta..H/sub ac/ was found to be 2.86 +/- 0.23 kcal/mole, with crystallization kinetics that were shown to be impurity concentration dependent, and in good agreement with literature values. A Gibbs free energy diagram for a-Si was derived and used to estimate the melting temperature of a-Si to be 1420 K.},
doi = {},
url = {https://www.osti.gov/biblio/6899275}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1982},
month = {1}
}

Thesis/Dissertation:
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