摘要:

A model of the growth of large bubbles in solids during ion implantation is presented. In this model, the random formation of “vacancies” or defect clusters in a lattice is simulated by Monte Carlo methods. Lattice defects within a certain cutoff distance of one another are assumed to coalesce and rearrange themselves in as near to spherical geometry as possible. This iterative process of coalescence and rearrangement continues until all defects are farther apart than the cutoff distance. Then a new random defect is introduced and the process continues. In this way, isolated defects agglomerate into the larger bubbles. This process, rather than the radiation displacement of atoms directly on the bubble surface, dominates the growth. It is found that the growth rate of the largest bubble is slow until a critical concentrationisreached, after which the bubble grows at an accelerated rate. The defect concentration and bubble density at which this occurs are in agreement with recent experimental evidence.

ISSN:0033-7579    

DOI:10.1080/00337577808242091

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Optical and conductivity measurements have been made on rutile (TiO2) samples implanted with 28 MeV deuterons and 56 MeV alpha particles. An assumption is proposed to explain the localization of the coloration at the end of the particles paths: chemical reactions of implanted deuterons imply the formation of Ti+3sites, which is not the case with implanted alpha particles. The oscillator strength of 10−3, deduced from optical absorption profiles, for the optical transition of the 1.35 μm absorption band in chemically implanted rutile supports the assignment of ad–dtransition localized at a Ti+3site for the “blue” band. The analysis of the distribution of conductivity along the particle path and infrared absorption measurements seem to conform this hypothesis.

ISSN:0033-7579    

DOI:10.1080/00337577808242092

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

An approximate analytical theory of the focusing of trajectories of channelled ions in the transverse plane is developed, following ideas found by computer simulation. Its use in interpreting experiments on the scattering of MeV ions from crystal surfaces at grazing incidence is demonstrated. Criteria for strong reflection and the angular width of reflection peaks are deduced. It is shown how surface structure analysis techniques might be developed, taking the case of oxygen in a tungsten {110} surface as an example.

ISSN:0033-7579    

DOI:10.1080/00337577808242093

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A Monte-Carlo code is described which simulates features of collision cascades due to ion bombardment. The effects of including an energy loss,U, from the recoiling atom during the displacement process is investigated for 0 ≤U≤Ed. Depending on whetherU= 0 orU=Edis used, the fraction of replacement collisions is determined as 0.28 or 0.19 respectively. Also the fraction of energy expended in elastic collisions and displacement events,v(E) is determined dependent upon the value ofU. These results are compared to transport theory solutions. Individual collision cascades are generated and quantitative values determined for the ratio between the individual cascade volume and the cascade volume obtained using the longitudinal and transverse moments of the deposited energy distributions evaluated from transport theory by Winterbon. These volume ratios are compared to the equivalent ratio's calculated by Sigmund.

ISSN:0033-7579    

DOI:10.1080/00337577808242094

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The vacancy defect subsystem is studied by means of electron microscopy in ion-implanted silicon. It has been discovered that, unlike the interstitial atoms which form rod-like defects and two-dimensional defects (dislocation loops, stacking faults), vacancies condense during annealing into three-dimensional associations—voids. The formation temperature of a void consisting of ∼103vacancies in 400–500°C. Voids have the tendency to associate into more complicated complexes; as a result of void interaction, disk-like clusters are formed in P+-implanted silicon. At temperatures 700–750°C, disk interaction is likely to take place which is accompanied by extended defect formation—chains. At annealing temperatures 800–850°C voids do not collapse in vacancy dislocation loops and chains do not rearrange in dislocations; all the defects dissolve in matrix.

ISSN:0033-7579    

DOI:10.1080/00337577808242095

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337577808242096

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor