Depth Distribution Of Impurities Research Articles

Segregation and increased dopant solubility in Pt-implanted and laser-annealed Si layers

Q-switched laser irradiation has been used to melt and recrystallize amorphous Pt-implanted layers formed on the surface of Si single crystals. While the Pt segregated to the surface by an effect related to zone refining, the final impurity depth distribution depended upon substrate temperature in the range 77–620 °K. This observation is correlated with calculations of changing melt dwell times and resolidification velocities. The nonuniform lateral distribution of the segregated Pt at the Si surface is believed to be controlled by constitutional supercooling occurring in the resolidifying melt. In addition, Pt exhibited considerable substitutionality in the Si lattice after laser annealing, corresponding to an effective solubility enhancement of 3 orders of magnitude. This phenomenon is correlated with solute trapping and melt viscosity effects occurring during resolidification.

Dose dependence in the laser annealing of arsenic-implanted silicon

In the laser annealing of silicon by Nd : YAG laser irradiation a dose dependence of the annealing threshold and final impurity depth distribution has been observed. Impurity depth distributions and damage profiles observed by Rutherford backscattering are consistent with the notion of the formation of a thin liquid layer and subsequent regrowth of the crystal upon cooling. We conclude that the annealing behavior is very sensitive to the time of formation of the liquid layer during the laser pulse.

後方散乱法を用いたマイクロアナリシス

A new microanalysis using backscattering method was applied to measure lateral distributions as well as depth distributions of impurities in semiconductors. High energy He+-beam from the Van de Graaff accelerator could be squeezed to 70500μmφ on the target by means of the quadrupole magnetic lens and slits system. The lateral distributions of impurities in semiconductors were measured by step scanning i.e, by using a goniometer which slides the targets along the direction perpendicular to the beam line with a minimum step of 10μm.The microanalysis was applied to measure the lateral and depth distributions of Au atoms at GaAs crystal surface sintered in the nitrogen atmosphere after Au evaporation to GaAs crystal surface. It was found that the lateral distributions were not uniform either on the surface or in the bulk. Au atoms were diffused abnormally to the deep region in GaAs crystals, and the concentration profiles of Au were not fitted to complementary error functions. Also presented are the measured results of distributions of Sn doped into Si by means of two different techniques, i.e, doped oxide method and CZ pulling method.

Investigation of the depth distribution of impurities by charged-particle activation

A method is described for the quantitative determination of the distribution of impurities, utilizing charged particles. Experimental data obtained by activation with 7.5 MeV3He ions are reported on the distribution of oxygen in Ge and Nb samples.

Heavy Ion-Induced Characteristic X-Ray Generation as an Analytical Probe

AbstractIncreasing attention is currently focused on the generation of characteristic x-ray by proton irradiation. This has the advantage of yielding “clean” x-ray- i. e. free from background brerasstrahlung radiation, from even the lightest elements. The disadvantage is that the yields are naturally much lower than those produced by electrons of the same energy. A recent study has extended characteristic x-ray production to a variety of heavy ions and has shown that the cross- sections for the production of clean x-rays are often higher , by as much as several orders of magnitude, than those produced by protons of the same energy. In addition, there has emerged a further advantage, viz. the ability of specially chosen heavy ions to excite characteristic x-ray from a particular element in a selective manner. Since heavy ions penetrate only a few hundred Angstroms in to most solids, the phenomenon can be used as the basis of a technique for the examination of surface deposits, or to measure depth distributions of impurities. For example, Kr ions can be used t o determine the range distribution of antimony which had been implanted in to silicon at 100 keV. The antimony concentration was determined as a function of ∼ 150 Å steps, and was found to exhibit a maximum concentration of ∼ 1 part in 103of silicon at 450 Å below the surface, falling to zero concentration at ∼2000 Å a depth. In the past, in order to obtain the required degree of sensitivity, such range determinations have relied on radio active tracer techniques.An entirely new type of proportional counter has been developed during the course of these studies. This instrument, because of its special construction, can be positioned very close to targets in non-dispersive studies, so as to collect the highest possible fraction of emitted x-ray. It incorporates a replaceable anode unit, together with a built- in miniature head amplifier, and exhibits extremely good performance, particularly for ultra-soft x-ray. In addition, rotation of a dial on the end of the counter body allows alteration of the active gas volume during operation, and so permits tuning into x-rays of a particular energy.

Microanalysis of flourine in zircaloy by the use of the [formula omitted] reaction

A method of determining flourine contamination on and below the surface of zircaloy by means of proton irradiation using a Van de Graaff accelerator and the detection of prompt gamma radiation from the 19 F( p, αγ) 16O reaction has been studied. Formulae for deriving depth distributions of impurities from the measured counting rate have been derived. The influence of energy straggling on the depth resolution has been studied. Both the total amount and the depth distribution have been measured on samples, which have undergone different treatments. Because of the high yield from the reaction used, a quantity of flourine less than 0.01 μg/cm 2 can be detected by this method.