H. Naramoto

Ion implantation and thermal annealing of α‐Al2O3 single crystals

The effects of ion implantation and post‐implantation thermal annealing of α‐Al2O3 have been characterized using ion scattering‐channeling techniques, and correlated with electron paramagnetic resonance (EPR) and microhardness measurements. Although most of the work was done on 52Cr implanted specimens, preliminary results have been obtained also for implanted 90Zr and 48Ti. For Cr implantation, the Al2O3 lattice damage saturates at relatively low doses, but the near‐surface region never becomes amorphous. A preferential annealing behavior begins in the Al sublattice after ∼800 °C annealing, and in the oxygen sublattice, only after 1000 °C annealing. Lattice location measurements show that after annealing to 1500 °C, Cr is greater than 95% substitutional in the Al sublattice. Above 1500 °C, implanted Cr atoms redistribute by substitutional diffusion processes. EPR measurements show that part, if not all, of the implanted Cr is trivalent and substitutional after annealing to 1600 °C. Microhardness measurem...

The amorphization of ceramics by ion beams

The influence of the implantation parameters fluence, substrate temperature, and chemical species on the formation of amorphous phases in Al/sub 2/O/sub 3/ and ..cap alpha..-SiC was studied. At 300/sup 0/K, fluences in excess of 10/sup 17/ ions.cm/sup -2/ were generally required to amorphize Al/sub 2/O/sub 3/; however, implantation of zirconium formed the amorphous phase at a fluence of 4 x 10/sup 16/ Zr.cm/sup -2/. At 77/sup 0/K, the threshold fluence was lowered to about 2 x 10/sup 15/ Cr.cm/sup -2/. Single crystals of ..cap alpha..-SiC were amorphized at 300/sup 0/K by a fluence of 2 x 10/sup 14/ Cr.cm/sup -2/ or 1 x 10/sup 15/ N.cm/sup -2/. Implantation at 1023/sup 0/K did not produce the amorphous phase in SiC. The micro-indentation hardness of the amorphous material was about 60% of that of the crystalline counterpart.

Ion implantation, ion beam mixing, and annealing studies of metals in Al2O3, SiC and Si3N4☆

Abstract Ion scattering/channeling, TEM, EPR and optical microscopy are utilized to determine the structural modifications of ion implanted and annealed Al2O3, SiC, and Si3N4, and to correlate these modifications to surface mechanical property measurements. Ion beam mixing is also studied for inducing increased adherence of metal films on these insulators.

Near surface modification of α-Al2O3 by ion implantation followed by thermal annealing☆

Abstract Structural changes in α-Al2O3 crystals implanted by 48Ti and 90Zr and subjected to thermal annealing have been investigated using ion scattering/channeling techniques. For the case of Ti implantation, the implanted species exhibits substitutionality in the as-implanted condition and undergoes anisotropic diffusion along the 〈0001〉 axis at a temperature of 1200°C which gives rise to the formation of needle-like precipitates partially coherent along the 〈0001〉 direction. For the case of Zr implantation, recovery of lattice damage begins in the Al sublattice at ∼ 800°C and in the O sublattice at ∼ 1300°C. Zr is not observed to be substitutional even after annealing to temperature of 1600°C. Results on the structural changes are correlated with measured mechanical property changes for the case of Cr, Ti, and Zr implanted into Al2O3 and thermally annealed to temperatures of 1600°C.

The structure and properties of ion-implanted A12O3☆

Abstract The effects of implantation temperature (77–640 K), ion species (Cr, Zr, Mb, Al + O, Xe), and fluence (1 × 1014 to 1 × 1017 ions cm−2) on the structure and surface hardness of A12O3 have been studied. Low temperatures favor the rapid accumulation of damage and formation of an amorphous layer. Except for zirconium, fluences in excess of 1 × 1017 ions cm −2 are required to amorphize A12O3 at 300 K. The amorphous phase has a hardness about 65% of that of the crystalline phase.

Alteration of Surface Properties by Ion Implantation

Some exploratory experiments involving the bombardment of semiconductor materials by high-energy ions to alter the electrical properties of these materials were conducted in the 1950s. Since then, ion implantation has become a standard processing technique in the semiconductor industry to introduce dopants into a wide range of materials. During the 1970s interest in this technique was extended to modification of the chemical or mechanical properties of metals and the optical and electrical properties of insulators. Reference 1 contains a set of reviews covering studies outside of semiconductor technology. This paper describes studies to extend the use of ion implantation techniques to modify the mechanical properties of structural ceramics.

Structure of Ceramic Surfaces Modified by Ion Beam Techniques

Modification of the near-surface region of materials by use of energetic ion beams has been investigated extensively in recent years. The nature of the process allows one to introduce any element into the near-surface region of solids in a controlled and reproducible manner that is independent of most equilibrium constraints. Since the process is nonequilibrium in nature, compositions and structures unattainable by conventional methods may be produced.

Modification of The Near-Surface Region Of Al 2 O 3 By Ion Implantation

Physical and structural property changes resulting from ion implantation and thermal annealing of α-A1 2 O 3 are reviewed. Emphasis is placed on damage production during implantation, damage recovery during thermal annealing, and impurity incorporation during thermal annealing. Physical and structural property changes caused by ion implantation and annealing are correlated with changes in the mechanical properties.