5157. Factors influencing the formation and growth of faulted loops in BF2+-implanted silicon

Classified abstracts 5149-51 58 structure. Post-thermal annealing at 500~C produces PtSi. A St-enriched me[as[able phase Pt,Si 3 is present after irradiation of PtzSi/Si or PISi/Si structure. Post-thermal annealing at 450~C produces the growth of Pt, Si ~. Further annealing at 500:C induces the formation of PtSi and Si polycrystal. (Italy) G Majni etal, J Appl Phys, 52 (6), 1981. 4055-4061. 35 5149. The role of plasma diffusion in heat dissipation during laser annealing. (USA) The role of the plasma contribution to the heat dissipation during laser annealing of monocrystalline silicon was investigated. The experiments were performed with a Q-switched ruby laser with a pulse length of 25-30 us. It was found that for samples with larger values for the minority carrier diffusion length, the threshold energy for annealing was increased and the depth of melting was reduced. The experimental results were compared with a thermal model which takes into account the modification of the distribution oflaser energy coupled to the lattice due to the diffusion of the minority carriers which occurs prior to recombination. It is concluded that, due to the significant reduction of the minority carrier diffusion length which occurs under the extremely high generation rates achieved during laser annealing, the plasma diffusion does not dominate the thermal behaviour. However, the effects of plasma diffusion can be observed experimentally and they should not be neglected in a completed description of the laser annealing process. L Jastrzebski et ul, J App/ Phys. 52 (6), 1981. 4276~1280. 35 5150. A study of Ge/GaAs interfaces grown by molecular beam epitaxy. (USA) Ohmic contacts to ,-GaAs using a Ge/GaAs heterojunction have been developed~ Ge layers with free-electron concentrations above 1 x 102° cm- 3 have been grown on GaAs by molecular beam epitaxy (MBE). Gold evaporated on such structures forms tunnel contacts through the Ge to the GaAs. The lower barrier height of metals on Ge compared to GaAs and the small barrior at the Ge/GaAs heterojunction facilitates the formation of contacts with specific contact resistances below 10 = ~ [ ' l cm'. R A Stall et al, J Appl Phys, 52 (6), 1981, 4062~-069. 35

5151. Trapping of Sb by TaC and Ca precipilates in ion-implanted Fe. (USA) Experimental evidence is presented for trapping of Sb by TaC and Cu precipitates in Fe. These processes were studied during annealing at 873 K of Fe ion-implanted with either Ta, C, and Sb, or Cu and Sb. For both precipitates the derived binding enthalpy is ~0A eV when referenced to an Sb solution site in the bcc-Fe phase. It is argued that this trapping occurs at the precipitate-host interface, and that it is due primarily to the associated structural discontinuity. In the Fe-Cu-Sb alloys, trapping was accompanied by two other processes which immobilize Sb, namely, dissolution into the fcc-Cu phase and formation offl~Cu 3Sb. The trapping effects observed in these studies are of potential significance for the control of Sb embrittlement in ferritic steels. S M Myers and D M Follstaedt, J App/Phys, 52 (6). 198I, 4007~4017. 35 5152. Stoichiometric disturbances in ion implanted compound semiconductors. (USA) Disturbances in the stoichiometry of compound semiconductors which result from ion implantation are calculated using a Boltzmann transport equation approach. Results for 50 keV boron. 150 keV silicon, and 400 keV selenium implanted into silicon carbide, indium phosphide, and gallium arsenide are presented. Possible complications in the annealing of such implants are discussed. L A Chris[el and J F Gibbons, J Appl Phys, 52 (8). 1981, 5050-5055. 35 5153. Laser annealing to produce ferroelectrie-phase PbTiOa thin films. (USA) PbTiO~ thin films with good ferroelectric properties have been prepared by rfsputtering at relatively low temperatures of ~ 350°C and subsequent laser annealing. The annealing has been done by cw CO2 laser irradiation at 10~40 W for 0.1 ~ 10 s. A distant phase change from the paraelectric Pyrochlore phase to the ferroelectric perovskite phase is induced by means of a solid-state reaction in the irradiated region without temperature rise of peripheral regions. The observed effect increases feasibility of producing new functional electronic devices employing ferroelectric thin films such as

nonvolatile memory field-effect transistors, infrared optical field-effect transistors, and imaging devices with a ferroelectric layer. (Japan) Yasushi Matsui etal, J Appl Phys. 52 (8), 1981, 5107-511i, 35

5154. On the formation of binary compounds in Au/InP system./USA) The formation and identification of binary compounds in Au-InP system has been reported. The contact reaction was investigated in the temperature range 320-360~C by the combined use of 2 MeV He + .ions backscattering spectrometry, X-ray diffraction, TEM and SEM. The results give evidence that both In and P form compounds with gold; formation of oxides has not been observed. A model of metallurgical structure of Au/InP contacts annealed at temperatures below or equal to 360"C has been proposed. (France) A Piotrowska etal, J Appl Plfys, 52 (8), 1981, 5112-5117, 35 5155. In-depth profiles of deep-trap concentration in Fe-implanted n-type silicon. (USA) A peak of deep-level transient-spectroscopyspectrum obtained from ironimplanted n-type silicon was investigated, and it was found that the apparent energy level of the trap varied as the distance from the implanted layer increased. This is due to a change, with the distance, of the concentration ratio of two kinds of traps, an implantation-induced (E 3: E¢ - 0.50 eV) a nd an iron-associated centre (E2 :E¢ - 0.58 eV).The Ez trap concentration showed an L-shaped in-depth profile. In the sample with p*-diffused layer on the surface opposite of the iron-implanted layer. the in-depth profile of the E z trap concentration was U shaped. These indepth profiles can be explained in terms of interstitial-substitutional diffusion of iron atoms. (Japan) Osamu Kumagai, J Appl Phys, 52 (8), 1981, 5143-5147. 35 5156. The reaction of fluorine atoms with silicon. (USA) Fluorine atoms etch silicon with a rate, Rrts~,=2.91 _+0.20 x 10-'2TItZnre°a°s'wkr A/rain. where nr (cm -~) is the atom concentration. This etching is accompanied by a ehemiluminesccnt continuum in the gas phase which exhibits the same activation energy. These phenomena are described by the kinetics: ( 1) Fu~+ Si~,,r~SiF2= ~ (2) SiF2~ l+ Fuf-b SiF~'~, (3) SIFz,g~+Fzt~--*S,Fz~+F~, (4) S1Fj
5157. Factors influencing the formation and growth of faulted loops in BF~-implanted silicon. (USA) Transmission electron microscopy has been applied to study faulted loops in BF~'-implanted silicon. (001)- and (I I I)-oriented silicon were irradiated by BF~" ions to doses of I x 1014-[ x 1015 cm -2 followed by annealing at 1000-1200°C in dry N2, dry Oz and wet 0 2 for different periods of time (I min to 2 h). The oxygen content in the annealing ambient was found to be of critical importance in the nucleation and growth of faulted loops. The presence of oxygen atoms lowered the activation energy for the nucleation of faulted loops and increased the heterogeneous nucleation sites as well as accelerated the growth of loops. For the same foil the difference in the growth rate of loops was explained in terms of the competition of the inflow of interstitial flux from the oxide/silicon interface and vacancy flux from the rest of silicon towards the interface. There was indication that the difference may arise because the defects were of different natures. Stress effect was invoked to discuss why faulted loops were more prominent in (001 )-oriented, lower-dose samples than in (111)-oriented, higher-dose samples, respectively. (Taiwan) L J Chen etal, J App/Phys, 52 (5), 1981, 3520-3527. 35 5158. Experimental and calculated depth distributions of dansage and projected ranges of 20 keV 4He ions in nickel. (USA) A recently improved sample-sectioningtechnique allowed us to obtain the entire depth distribution of damage (e.g., cavities) produced by 20 key '*He+ ions injected into annealed, poiycrystalline nickel held at 500°C. We have also obtained the depth profile of the implanted helium con~lftration using the elastic recoil detection technique. These experimental depth profiles have been used to test several theoretical predictions for 45~