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A theoretical investigation is made into the structure and properties of complexes formed between boron and othercommon impurities in Si,namely hydrogen,oxygen and carbon. Particular emphasis is placed on identifying the centreswith those observed experimentally. It is shown that B i B s ; an electrically inert defect that can be identified with theinfrared absorption Q-centre,can readily bind a hydrogen atom. B i B s H may then be responsible for the E v þ0:51 eVacceptor level seen in irradiated Si that contains hydrogen. B i O i has a (0/+) level close to E c 0:23 eV and may bedetected after the loss of B i : The anneal of B i O i can lead to the formation of B i C s which is stable to B400 C and has alevel near E v þ0:29eV:r 2003 Elsevier B.V. All rights reserved. PACS: 61.72.Bb; 61.72.Ji; 71.55. i; 71.15.Nc; 61.72.TtKeywords: Boron; Silicon; Interstitial; Defects 1. IntroductionAs the semiconductor device industry drivestoward ever smaller devices,the need for extremelyhigh doping in tightly defined regions becomesever greater. One way to achieve such a regime isby ion-implantation of the dopant,often boron.However,the energy transferred to the crystalduring this implantation creates much damage inthe form of Frenkel pairs leading to the creation ofvacancy and interstitial clusters along with theundesired phenomena of transient enhanced diffu-sion (for example, Refs. [1,2]). For boron,inter-stitial clusters dominate and these have beeninvestigated in great detail although the assign-ment of observed centres to specific clusters is stillat an early stage [3].B |
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