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7245. A low cost ion beam profile
Clas~',fied abstracts 7 2 4 5 - 7 2 5 4
efl'ective method of simultaneous exposure at every beamlinc is also discussed. H Takada and T Tomimasu, J Phys D : Appl Phys, 23, 1990, 631 636. 30 7245. A low cost ion beam profile monitor A n intercepting multiwire ion beam profile monitor, of thickness 0.9 cm and active area 5 × 5 cm, has been developed for use with the low-intensity deuteron beamline at the Fast Neutron Research Facility (FNRF), University of Chiang Mat. It has been used to optimise the transport of a continuous ion beam of current up to 200/~A and kinetic energy up to 140 keV. The monitor enables the determination of the two-dimensional beam profile using closely-spaced samples at 1.5 ram, and the measurement of relative beam current. The design incorporates low material and labour costs, elimination of the need t'or commercial vacuum feedthroughs, a minimal a m o u n t of devoted electronics with no need for preamplifiers, and permits quick insertion of the monitors, wherever needed along the beamline, with m i n i m u m disruption to neighbouring elements. L Godfrey et al, Nucl lnstrum Meth Phys Res, B51, 1990, 294 300. 30 7246. Identification and purification of multicharged silicon ion beams Reactions during beam transport between ions and residual gas molecules in the beamline lead to higher charge state ions mixing with lower charge state ions at a lower energy. This in turn leads to ion beams of nonunique energy. In this paper we describe experimental results in the identification and purification of multicharged silicon ion beams using electrostatic analysis. M Ma et al, Nucl lnstrum Meth Phys Res, B51, 1990, 53 57. 3(1 7247. Ion production from LiF-coated field emitter tips Ion emission has been obtained from a LiF-coated tungsten field-emitter tip. Ion formation is thought to be caused by the high electric field experienced by the LiF. At the time of emission the electric field at the surface of the LiF is calculated to be in the order of 100 MV cm ~. Inside the LiF the field is in the order of 10 MV cm ~. These fields exceed the value needed to produce bulk dielectric breakdown in LIP'. The surface field is of sufficient magnitude to produce ion emission by field evaporation from the crystal surface. Even prior to dielectric breakdown, precursor processes can lead to ion formation. Electric-field-stress fragmentation of the LiE layer is thought to occur, followed by ionization of the fragments. A L Pregenzer et al, J Appl Phys, 67, 1990, 7556 7559. 31. ION I M P L A N T A T I O N OF S E M I C O N D U C T O R S 31 7248. Silicon-on-insulator: materials aspects and technological applications Materials and techniques to obtain silicon-on-insulator structures are presented including a brief discussion on the physical principles of each technique. The advantages and limitations of the various silicon-oninsulator materials for technological applications in the development of future electron devices and Very Large Scale Integrated circuits are discussed. G Bomchil, Vacuum, 41, 1990, 781 783. 31 7249. Surface regrowth of implantation damaged Get111) Annealing induced surface recrystallization of Sb implanted Get1111 has been investigated by means of A R U P S , LEED and RBS. Our results show this process starts at a relatively low temperature (300'C), but a disordered surface layer persists even after high temperature annealing (650'C). By removing a 5 17 23 thick surface layer before each thermal annealing, a nearly epitaxially regrown surface was obtained. G Pet6 et ai, Vacuum, 41, 1990, 618 620. 31 7250. Changes in hydrophobic properties of glass surfaces by ion implantation Ion implantation was used to modify the hydrophobic properties of glass surfaces. The hydrophobicity of the glass surface was evaluated by contact angle measurements for water droplets as a function of ion implantation conditions. The results showed, irrespective of ion species, that the contact angle was influenced by the energy and dose of primary ions and atmospheric conditions. A m a x i m u m contact angle of 80' was 576
obtained after ion implantation with an energy of 50 I00 keV and a dose of I0 ~5 10 ~7 ions cm 2 though the contact angle before ion implantation was around 1 0 20' for soda-lime glass. Characterization ofhydrophobic glass surfaces thus prepared has been carried out by X-ray photoelectron spectroscopy (XPS). XPS analysis revealed the t`ormation of carbonrelated bonds such as C - - H and C - - H 2 at the glass surface, which could be explained in terms of the interaction between primary ions and adsorbed species on the glass surface. In conclusion, hydrophobic glass surfaces were obtained by the formation of carbon-related bonds as a result of ion implantation. T Ohwaki and Y Taga, J Vac Sci Technol, A8, 1990, 2173 2178. 31 7251. Gold implantation in n-type silicon: entropy factor and diffusion studies Rutherford backscattering spectrometry and spreading resistance techniques have been used to determine the concentration profiles of gold implanted and diffused in n-type silicon. Diffusion has been performed at 1243 K for times ranging between I and 20 h in a dry-nitrogen flux. Resistivity profiles were transformed into concentration profiles by solving the charge balance equation. The entropy factor for the ionization of gold acceptor level was determined to be 5 0 + 5. By using this value and solving the charge balance equation we have calculated the silicon resistivity vs gold concentration (and therefore minority-carrier lifetime) curves as a function of the resistivity of the starting material. Experimental gold concentration profiles were compared to the profiles obtained by numerical solution of the diffusion equation for gold in silicon. The measured diffusion coefficients coincide with the values determined ['or p-type material. S Coffa et al, J Appl Phys, 68, 1990, 1601 1605.
31 7252. Deep levels in undoped bulk InP after rapid thermal annealing Deep levels in rapid thermal annealed lnP in metal-insulator-semiconductor (M1S) structures have been studied using deep level transient spectroscopy. Two different insulating layers used in forming M1S structures, a silicon nitride layer and an oxide layer, were fabricated by plasma enhanced chemical vapor deposition and concentrated nitric acid, rcspeclively. In the samples annealed at temperatures between 700 and 900"C for 10 s, two deep levels having apparent energy depths of 0.43 and 0.35 eV below the conduction band were newly generated. Then, it is considered that they are the defects related with phosphorus vacancy and its complex. Other deep levels observed between I).55 and 0.79 eV below the conduction band were related with insulating layers. We show evidence that they might be interface states in the junction of lnP and insulator. Enu Kyu Kim et ai, J App/Phys, 68, 1990. 1665 1668. 31 7253. Radiation damage annealing models in glass detectors The thermal annealing behaviour of heavy ions and fission fragment tracks in sodalime, phosphate, and silicate glass is studied. A review on thermal annealing formula is given. A simplified empirical lk)rmula is derived, comprising both isochronal as well as isothermal annealing procedures. G Singh and H S Virk, Radiat E~I 114, 19911, 51 62. 3[ 7254. One-step surface implantation and reaction by laser irradiation of multistructures deposited on Si and Ge samples We report the surface implantation with boron of St and Ge by multipulse XeCI excimer (2 308 nm) or by low-power cw CO2 (,;~ = 10.6 #m) laser irradiation of St and Gc wafers covered with a thin ( ~ 10 nm) boron film. In view of minimizing the boron losses by ablation or the boron oxidation in air, the boron deposition on semiconductor wafers was protected with a SiO2 film when the excimer laser was used. In a further experiment we have submitted to pulsed laser irradiation SiO 2 Ti B structures deposited on Si and Ge wafers, aiming tbr both B implantation and the reaction of Ti with the semiconductor at the interface to form a silicide layer. The irradiated samples were examined by optical and electron microscopy and then investigated by RBS and SIMS techniques. Sheet resistance was measured and the p n characteristics of the formed junctions were recorded. For the first time with pulsed laser processing a p n junction with boron in germanium was obtained, showing quite good electrical characteristics (breakdown voltage of ~ 4 0 V and leakage current of ~ I
efl'ective method of simultaneous exposure at every beamlinc is also discussed. H Takada and T Tomimasu, J Phys D : Appl Phys, 23, 1990, 631 636. 30 7245. A low cost ion beam profile monitor A n intercepting multiwire ion beam profile monitor, of thickness 0.9 cm and active area 5 × 5 cm, has been developed for use with the low-intensity deuteron beamline at the Fast Neutron Research Facility (FNRF), University of Chiang Mat. It has been used to optimise the transport of a continuous ion beam of current up to 200/~A and kinetic energy up to 140 keV. The monitor enables the determination of the two-dimensional beam profile using closely-spaced samples at 1.5 ram, and the measurement of relative beam current. The design incorporates low material and labour costs, elimination of the need t'or commercial vacuum feedthroughs, a minimal a m o u n t of devoted electronics with no need for preamplifiers, and permits quick insertion of the monitors, wherever needed along the beamline, with m i n i m u m disruption to neighbouring elements. L Godfrey et al, Nucl lnstrum Meth Phys Res, B51, 1990, 294 300. 30 7246. Identification and purification of multicharged silicon ion beams Reactions during beam transport between ions and residual gas molecules in the beamline lead to higher charge state ions mixing with lower charge state ions at a lower energy. This in turn leads to ion beams of nonunique energy. In this paper we describe experimental results in the identification and purification of multicharged silicon ion beams using electrostatic analysis. M Ma et al, Nucl lnstrum Meth Phys Res, B51, 1990, 53 57. 3(1 7247. Ion production from LiF-coated field emitter tips Ion emission has been obtained from a LiF-coated tungsten field-emitter tip. Ion formation is thought to be caused by the high electric field experienced by the LiF. At the time of emission the electric field at the surface of the LiF is calculated to be in the order of 100 MV cm ~. Inside the LiF the field is in the order of 10 MV cm ~. These fields exceed the value needed to produce bulk dielectric breakdown in LIP'. The surface field is of sufficient magnitude to produce ion emission by field evaporation from the crystal surface. Even prior to dielectric breakdown, precursor processes can lead to ion formation. Electric-field-stress fragmentation of the LiE layer is thought to occur, followed by ionization of the fragments. A L Pregenzer et al, J Appl Phys, 67, 1990, 7556 7559. 31. ION I M P L A N T A T I O N OF S E M I C O N D U C T O R S 31 7248. Silicon-on-insulator: materials aspects and technological applications Materials and techniques to obtain silicon-on-insulator structures are presented including a brief discussion on the physical principles of each technique. The advantages and limitations of the various silicon-oninsulator materials for technological applications in the development of future electron devices and Very Large Scale Integrated circuits are discussed. G Bomchil, Vacuum, 41, 1990, 781 783. 31 7249. Surface regrowth of implantation damaged Get111) Annealing induced surface recrystallization of Sb implanted Get1111 has been investigated by means of A R U P S , LEED and RBS. Our results show this process starts at a relatively low temperature (300'C), but a disordered surface layer persists even after high temperature annealing (650'C). By removing a 5 17 23 thick surface layer before each thermal annealing, a nearly epitaxially regrown surface was obtained. G Pet6 et ai, Vacuum, 41, 1990, 618 620. 31 7250. Changes in hydrophobic properties of glass surfaces by ion implantation Ion implantation was used to modify the hydrophobic properties of glass surfaces. The hydrophobicity of the glass surface was evaluated by contact angle measurements for water droplets as a function of ion implantation conditions. The results showed, irrespective of ion species, that the contact angle was influenced by the energy and dose of primary ions and atmospheric conditions. A m a x i m u m contact angle of 80' was 576
obtained after ion implantation with an energy of 50 I00 keV and a dose of I0 ~5 10 ~7 ions cm 2 though the contact angle before ion implantation was around 1 0 20' for soda-lime glass. Characterization ofhydrophobic glass surfaces thus prepared has been carried out by X-ray photoelectron spectroscopy (XPS). XPS analysis revealed the t`ormation of carbonrelated bonds such as C - - H and C - - H 2 at the glass surface, which could be explained in terms of the interaction between primary ions and adsorbed species on the glass surface. In conclusion, hydrophobic glass surfaces were obtained by the formation of carbon-related bonds as a result of ion implantation. T Ohwaki and Y Taga, J Vac Sci Technol, A8, 1990, 2173 2178. 31 7251. Gold implantation in n-type silicon: entropy factor and diffusion studies Rutherford backscattering spectrometry and spreading resistance techniques have been used to determine the concentration profiles of gold implanted and diffused in n-type silicon. Diffusion has been performed at 1243 K for times ranging between I and 20 h in a dry-nitrogen flux. Resistivity profiles were transformed into concentration profiles by solving the charge balance equation. The entropy factor for the ionization of gold acceptor level was determined to be 5 0 + 5. By using this value and solving the charge balance equation we have calculated the silicon resistivity vs gold concentration (and therefore minority-carrier lifetime) curves as a function of the resistivity of the starting material. Experimental gold concentration profiles were compared to the profiles obtained by numerical solution of the diffusion equation for gold in silicon. The measured diffusion coefficients coincide with the values determined ['or p-type material. S Coffa et al, J Appl Phys, 68, 1990, 1601 1605.
31 7252. Deep levels in undoped bulk InP after rapid thermal annealing Deep levels in rapid thermal annealed lnP in metal-insulator-semiconductor (M1S) structures have been studied using deep level transient spectroscopy. Two different insulating layers used in forming M1S structures, a silicon nitride layer and an oxide layer, were fabricated by plasma enhanced chemical vapor deposition and concentrated nitric acid, rcspeclively. In the samples annealed at temperatures between 700 and 900"C for 10 s, two deep levels having apparent energy depths of 0.43 and 0.35 eV below the conduction band were newly generated. Then, it is considered that they are the defects related with phosphorus vacancy and its complex. Other deep levels observed between I).55 and 0.79 eV below the conduction band were related with insulating layers. We show evidence that they might be interface states in the junction of lnP and insulator. Enu Kyu Kim et ai, J App/Phys, 68, 1990. 1665 1668. 31 7253. Radiation damage annealing models in glass detectors The thermal annealing behaviour of heavy ions and fission fragment tracks in sodalime, phosphate, and silicate glass is studied. A review on thermal annealing formula is given. A simplified empirical lk)rmula is derived, comprising both isochronal as well as isothermal annealing procedures. G Singh and H S Virk, Radiat E~I 114, 19911, 51 62. 3[ 7254. One-step surface implantation and reaction by laser irradiation of multistructures deposited on Si and Ge samples We report the surface implantation with boron of St and Ge by multipulse XeCI excimer (2 308 nm) or by low-power cw CO2 (,;~ = 10.6 #m) laser irradiation of St and Gc wafers covered with a thin ( ~ 10 nm) boron film. In view of minimizing the boron losses by ablation or the boron oxidation in air, the boron deposition on semiconductor wafers was protected with a SiO2 film when the excimer laser was used. In a further experiment we have submitted to pulsed laser irradiation SiO 2 Ti B structures deposited on Si and Ge wafers, aiming tbr both B implantation and the reaction of Ti with the semiconductor at the interface to form a silicide layer. The irradiated samples were examined by optical and electron microscopy and then investigated by RBS and SIMS techniques. Sheet resistance was measured and the p n characteristics of the formed junctions were recorded. For the first time with pulsed laser processing a p n junction with boron in germanium was obtained, showing quite good electrical characteristics (breakdown voltage of ~ 4 0 V and leakage current of ~ I