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The results of a study of laser-annealed Au-Ge ohmic contacts to GaAs are presented. The specific contact resistivity was observed to decrease with increasing laser energy density while the grain size of the polycrystalline microstructure (as observed by transmission electron microscopy) increased. At higher energy densities, both parameters were found to remain constant within the experimental conditions used. Transmission electron micrographs, and sputtering Auger electron spectroscopic data showing Ga, As, and Ge redistribution within the Au-Ge film are also presented.

A series of compressive load relaxation experiments were conducted on germanium single crystals in the temperature range 400 to 885° C. The curvature of the logσ-log $$\dot \in $$ data obtained from load relaxation tests changes from concave upward to concave downward as the test temperature increases at fixed stress level, or as the strain level increases at fixed temperature. At intermediate temperatures, ∼600° C, the transition from concave upward to concave downward curvature happens on a single relaxation curve. These observations are consistent with the two-branch rheological model proposed by Hart to explain the deformation behaviour of metals and were analysed in terms of this model. The transition from concave upward to concave downward curvature could be moved to higher temperature by doping germanium with gallium, which decreases the dislocation glide velocity relative to that in pure germanium. The transition could be shifted to lower temperature by compressing samples along [1 $$\bar 1$$ 1] rather than [1 $$\bar 1$$ 0] because the [1 $$\bar 1$$ 1] orientation favours cross-slip while the [1 $$\bar 1$$ 0] orientation does not. Dislocation dipoles and straight dislocations dominated the microstructure of samples which had concave upward logσ-log $$\dot \in $$ curves, while well-developed dislocation cell structures dominated the microstructure of samples which yielded concave downward curves. The observed changes in the curvature of the load relaxation curves and the dislocation structure both indicate the increased importance of dislocation climb with increasing temperature. When compared through the Orowan equation, the load relaxation results are in good agreement with published stress-dislocation velocity data.

Formation of Mo/Si contacts by implantation of phosphorus ions was studied. The implantation was carried out at temperatures of −196, 25, and 150 °C and a fluence ranging between 1015 and 1017 ions cm−2. The morphological and structural characterizations were done with scanning electron microscopy, transmission electron microscopy, and x‐ray diffraction. Hexagonal MoSi2 phase was identified in samples implanted with more than 1016 ions cm−2 at all three implantation temperatures. Traces of MoP were found in the sample implanted with 1017 ions cm−2 at 150 °C. Measured effective contact resistance showed ohmic behavior in as‐implanted samples except for samples implanted with 1015 ions cm−2 at 150 °C. Smooth surfaces of implanted MoSi2 structures remained after post‐implant annealing at 850 °C for 1/2 h in H2 ambient. The effect of post‐implant annealing is also discussed in terms of doping, microstucture, and contact resistance.

Faulted dipoles ranging in height from 3 to 12 nm in high-purity Ge have been studied by lattice-fringe and weak-bean transmission electron microscopy techniques. Only intrinsic, Z-shape faulted dipoles were observed. Lattice-fringe images of large faulted dipoles, weak-beam images of faulted dipoles, and weak-beam images of faulted dipoles, and weak-beam images of near-edge dislocations yield stacking-fault energies of 78±14 mJ m−2, respectively. When determined from the height and width of faulted dipoles viewed end-on in lattice-fringe images, the value for the stacking-fault energy calculated from anisotropic elasticity theory increases from 78 to 160 mJ m−2 as the height decreases from 6 to 3nm.

Weak-beam transmission electron microscopy studies in Si and Ge have indicated dislocations which have recently been proposed to be dissociated when they lie on the glide plane but constricted when they lie on the shuffle plane. Reported observations of constricted segments rather than the isolated cusps or constrictions along faulted dipoles in Ge are recorded herein. Models of possible configurations for a faulted dipole with a constricted segment are presented, and at least three different mechanisms are proposed for the formation of the constricted length of the faulted dipole. (BLM)

Solid phase regrowth of Si on sapphire has been investigated in the Si (amorphous)/Al (poly)/Al2O3 (crystal) system. Using transmission electron microscopy, scanning electron microscopy, Auger electron spectroscopy, and Hall‐effect measurements, it has been shown that Si is transported through an Al film at 550 °C to produce p‐type Si films on the sapphire substrate. The growth process has been shown to be initiated at Si nucleation sites on the substrate. These sites expand by mass accretion, forming island structures that coalesce to yield continuous large grained polycrystalline Si films on the sapphire surface.Solid phase regrowth of Si on sapphire has been investigated in the Si (amorphous)/Al (poly)/Al2O3 (crystal) system. Using transmission electron microscopy, scanning electron microscopy, Auger electron spectroscopy, and Hall‐effect measurements, it has been shown that Si is transported through an Al film at 550 °C to produce p‐type Si films on the sapphire substrate. The growth process has been shown to be initiated at Si nucleation sites on the substrate. These sites expand by mass accretion, forming island structures that coalesce to yield continuous large grained polycrystalline Si films on the sapphire surface.

Amorphous silicon has been produced on a single‐crystal silicon surface that was exposed to intense pulsed UV‐laser radiation at 266 nm. In addition, the formation of an oxide several tens of nanometers in thickness is observed when the irradiation takes place in an O2 or in an air ambient. Various experimental techniques including transmission electron microscopy, sputtered Auger electron spectroscopy, and differential Fourier‐transform IR spectroscopy have been employed to characterize the laser‐induced amorphous silicon and the oxide layer formed by this rapid melting and resolidification process. The present study suggests a new oxidation phenomena, namely, ’’laser‐induced oxidation.’’

Q‐switched laser irradiation has been used to anneal O+‐implanted silicon to form SiO2 layers. Results of differential Fourier‐transformed infrared spectroscopy and transmission electron microscopy confirm the formation of oxide layers. Segregation of oxygen toward the surface was observed by secondary ion mass spectroscopy and correlated with resolidification velocities, which vary as a function of laser energy densities.

Characteristics of CW Ar-ion laser annealed InSb has been studied; properties include stoichiometric composition analysis and electrical C-V measurements. The stoichiometry compositions of laser-annealed samples at different power levels and scan speeds have been studied using an electron microprobe technique. Results were compared with electrical C-V measurements using MOS structures.

In this paper we treat surface tension driven convection effects in pulsed laser formed melts. Mass transport is determined from an approximate solution of the Navier Stokes equation. It is shown that for small laser spot diameters the characteristic mixing times are on the order of 100's of ns. The dependence of the convection mechanism on material and laser parameters is discussed and extended to thin metal films on Si. Experimental results substantiating the theoretical considerations are presented.

Amorphous silicon has been produced on a single crystalline silicon surface by intense UV laser radiation at 266 nm followed by rapid quenching. In addition, formation of oxide of several tens of nanometers has been observed when irradiation takes place in air or in O2 ambient. Various experimental techniques including Transmission Electron Microscopy (TEM), sputtered Auger Electron Spectroscopy (AES), and differential Fourier-transform IR spectroscopy (FT-IR) have been employed to study adsorption of oxygen during rapid melting and resolidification process. The present results suggest a new processing technique for forming thin oxide film, namely, “Laser-induced oxidation.”

Selective absorption, using patterned dielectric films, and beam shaping were used as means for improving the recrystallization of LPCVD polysilicon islands on fused quartz. IR imaging of the laser heated region was used to optimize and control the recrystallization. MOSFETs were fabricated in laser-recrystallized silicon islands on amorphous substrates using a standard n-channel poly-gate process. Devices with various channel lengths and widths were fabricated, and the dependence of threshold voltage, channel mobility, and leakage on recrystallization conditions and device dimensions was studied.

High-dose ion implantation (1017 ions-cm−2) of C+, N+, and O+ at 50 KeV into silicon followed by pulsed laser annealing at 1.06 μm was studied. Formation of SiC, Si3N4, and SiO2 has been observed and investigated using Transmission Electron Microscopy (TEM) and Differential Fourier-Transform Infrared (FT-IR) Spectroscopy. Furthermore, in N+-implanted and laser-annealed silicon samples, we have observed a cell-like structure which has been identified to be spheroidal polycrystalline silicon formed by the rapid laser irradiation.

The characteristics of MOSFET's fabricated in laser-recrystallized silicon islands on amorphous substrates using a standard n-channel poly-gate process were studied. Selective absorption using patterned dielectric films and beam shaping were used as means for improving the recrystallization of LPCVD polysilicon islands on fused quartz. IR imaging of the molten region was used to optimize and control the recrystallization. Devices with various channel lengths and widths were fabricated and the dependence of threshold voltage, channel mobility, and leakage on recrystallization conditions were studied.