Annealing behaviour of GaAs implanted with 70 MeV 120Sn ions

Journal of Physics and Chemistry of Solids, 1983

High resolution Rutherford backscattering-channeling (RBSC) and transmission electron microscopy (TEM) have been used to investigate the annealing behavior of Se implanted Cr-doped C&As layers. Two distinct annealing stages were observed; one at 250°C which is associated with amorphous zone annihilation and/or onset of solid phase epitaxial growth and the other at about 40&5OO"C, depending on the dose, that can be related to the dissociation of microtwins. Above SOO'C, the residual defects are primarily dislocation loops and precipitates. The calculated number of atoms associated with the precipitates has been found to correspond closely to the number of implanted atoms, implying 100% precipitation for the cases studied in this work. This could explain the poor or nonexistent electrical activation of Se after low temperature annealing (-6OO"C), even though good regrowth of the amorphous layer has taken place. Experiments with high purity GaAs produced the same result, as far as the observed residual damage was concerned, thus eliminating speculation about the involvement of Cr in the nucleation of microtwins. Transmission electron microscopy investigations of the amorphous-crystalline interface in the as-implanted samples failed to reveal any extended defects. In the present paper, we discuss various mechanisms that could be responsible for the formation of twins in low temperature annealed GaAs.

Journal of Applied Physics, 1981

Channeling and transmission electron microscopy have been used to investigate the parameters that govern the extent of damage in ion-implanted GaAs and the crystal quality following capless furnace annealing at low temperature (-400 •q. The implantation-induced disorder showed a strong dependence on the implanted ion mass and on the substrate temperature during implantation. When the implantation produced a fully amorphous surface layer the main parameter governing the regrowth was the amorphous thickness. Formation of microtwins after annealing was observed when the initial amorphous layer was thicker than 400 A. Also, the number of extended residual defects after annealing increased linearly with the initial amorphous thickness and extrapolation of that curve predicts good regrowth of very thin (< 400 A) GaAs amorphous layers produced by ion implantation. A model is presented to explain the observed features of the low-temperature annealing of GaAs.

Radiation Measurements, 2003

Single-crystal semi-insulating GaAs substrates implanted with 70 MeV 56 Fe ions with uences varying from 5 × 10 12 to 1 × 10 14 ions=cm 2 , have been investigated by optical transmission over photon energy range 0.1-1:4 eV. The density of radiation-induced defect states shows a considerable increase for the uences above 5 × 10 13 ions=cm 2 . Annealing studies of the sample having the uence of 1 × 10 14 ions=cm 2 show that signiÿcant damage recovery occurs over the temperature range 100 -500 • C with activation energy of annealing to be 0:19 eV. The mid gap defect states are annealed out more rapidly than the near band edge defect states during annealing up to 350 • C whereas the near band edge defect states are annealed out more rapidly than mid gap defect states during annealing between 350 • C and 600 • C.

Radiation …, 2003

Single-crystal semi-insulating GaAs substrates implanted with 70 MeV 56 Fe ions with uences varying from 5 × 10 12 to 1 × 10 14 ions=cm 2 , have been investigated by optical transmission over photon energy range 0.1-1:4 eV. The density of radiation-induced defect states shows a considerable increase for the uences above 5 × 10 13 ions=cm 2. Annealing studies of the sample having the uence of 1 × 10 14 ions=cm 2 show that signiÿcant damage recovery occurs over the temperature range 100-500 • C with activation energy of annealing to be 0:19 eV. The mid gap defect states are annealed out more rapidly than the near band edge defect states during annealing up to 350 • C whereas the near band edge defect states are annealed out more rapidly than mid gap defect states during annealing between 350 • C and 600 • C.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1993

Wafers of (100) GaAs have been implanted with 140 keV Zn`ions at off-channeling direction up to a fluence of 1 x 10 14 cm -2 . The target temperature wac kept at 110± l fl°t^. The defect clusters and the damage depth distributions were investigated by planar and cross-sectional high-r ;solution transmission electron microscopy (HRTEM and XHRTEM) and were modelled by a MAR-LOWE-based computer , ode. The experimental mean depth of the damage profile located at about 85 nm excee;is the calculated deposited energy and v,cancy distributions by more than 50% . The correlation between the deposited energy density within the cascade and the inn, structure of the observed defect clusters is discussed .

2009

Computer simulation and analysis of our data compared to published results on the activation of impurity dopants in GaAs, have lead to the establishment of a theoretical model for the electrical properties of GaAs doped by ion implantation and annealed using rapid thermal annealing. A comparison of the behavior of different dopant species have shown that all implants in GaAs have almost the same activation mechanism except for the amphoteric Si implants where electrical activity increased normally with annealing times and temperature up to 900°C, then decreased showing that a compensating mechanisms taking place at temperature higher than 850°C. Finally the Si implanted GaAs become P type for longer annealing times at high temperatures. The purpose of our work was to establish a theoretical model capable of explaining the behavior of Si dopants in GaAs, from relationship between the annealing conditions of Si in GaAs and the electrical properties of Si implanted in GaAs.

Vacuum, 2005

GaAs crystals with dislocation density smaller than 10 3 cm À2 were implanted at room temperature with 1.5 MeV Se + ions with doses ranging from 3 Â 10 12 to 3 Â 10 15 cm À2 : The samples were studied with a number of X-ray diffraction methods realized using synchrotron radiation, in particular recording of rocking curves with 50 Â 100 mm 2 probe beam and with Bragg-case section topography. The strain profiles were determined by fitting the theoretical rocking curves obtained by numerical integration of the Takagi-Taupin equations. The investigation revealed two different components of ion-induced strain. For doses up to 3 Â 10 14 cm À2 the strain profiles were dominated by a component caused by interstitial atoms with almost constant strain close to the surface. A second component directly corresponding to the depth distribution of implanted Se atoms was observed for the higher ion doses. Crystal amorphization was not yet observed for all applied doses. The comparative studies of similarly implanted Ge crystals did not exhibit the saturation of implantation induced strain. The amorphization of Ge crystals took place for relatively small dose of 6 Â 10 13 cm À2 : This difference is most probably caused by increased mobility of point defects observed close to 300 K.

Journal of Applied Physics, 2003

GaAs and InP crystals ion implanted with Si were athermally annealed by exposing each crystal at a spot of ∼2 mm diameter to a high-intensity 1.06 μm wavelength pulsed laser radiation with ∼4 J pulse energy for 35 ns in a vacuum chamber. As a result a crater is formed at the irradiated spot. The crater is surrounded by a dark-colored ring-shaped region which is annealed by mechanical energy generated by rapidly expanding hot plasma that formed on the exposed spot. The electrical characteristics of this annealed region are comparable to those of a halogen-lamp annealed sample. No redistribution of impurities due to transient diffusion is observed in the implant tail region. In x-ray diffraction measurements, a high angle side satellite peak due to lattice strain was observed in the crater and near crater regions of the athermally annealed sample in addition to the main Bragg peak that corresponds to the pristine sample. This high angle side satellite peak is not observed in regions a...

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1996

MeV Auf+ ions have been implanted into semi-insulating GaAs( 100) single crystal wafers to a dose of 1.5x lOI atoms/cm* at a tilted geometry. Samples were subsequently annealed in vacuum in the temperature range of 500 to 85O'C. PIXE and XRF measurements, carried out with 2.61 MeV Ht and 14.8 keV X-rays respectively, indicate practically no As loss from the implanted region. A significant As loss from the unimplanted region has been measured. Optical micrographs taken on both the implanted and the unimplanted regions show the formation of Ga droplets on the unimplanted region above 6OO'C annealing. However, no such features were observed in the implanted region up to 850°C. This indicates that MeV Au ion implantation inhibits the As release from GaAs. For a given annealing temperature and duration the amount of As loss depends on the dose of implanted Au. A tentative explanation for these results is presented. * Corresponding author.

Materials Science and Engineering: B, 1995

Silicon diffusion was carried out from a thin (50 nm) sputtered film into undoped semi-insulating and Te-or Zn-doped LEC-GaAs at 900 °C for 5 h under various As pressures. Secondary ion mass spectroscopy and spreading resistance technique were used to characterize the Si indiffusion profiles. Lattice defects in highly Si-doped diffusion regions were examined as a function of postdiffusion heat treatments (first at 700 °C for 15 min and second at 1000 °C for 30 min) by using transmission electron microscopy of plan-view and cross-sectional samples. Two types of defect were observed in the diffusion region: (i) perfect prismatic loops on {110} planes and of the interstitial type and (ii) Frank faulted loops on {111} planes, also of the interstitial type. A model for the defect formation and the role of Si in the defect generation are discussed in terms of a negative temperature dependence of thermal equilibrium concentrations of VG~, 3-, which are assumed to mediate the Si diffusion under high n-doping conditions. Cathodoluminescence spectra measured at 4 K and 77 K were obtained from the diffusion layer. Si diffusion affects the band-gap luminescence and generates two deep-level emission bands in the 0.9-1.3 eV spectral region. It is suggested that these deep levels are associated with some diffusion-induced defects and defect complexes.