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ELECTRONIC LEVELS-AND PROPERTIES OF THE SELFINTERSTITIALS IN IRRADIATED SILICON Kh.A.Abdullin, B.N.Mukashev, M.F.Tamendarov, and T.B.Tashenov Physical-Technical Institute, Kazakh Academy of Sciences, 480082, Alma-Ata, Republic of Kazakhstan ABSTRACT DLTS studies of electronic states and properties of the selfinterstitial in a-irradiated p-Si and n-Si are performed. The injection-enhanced annealinq is observed for two traps E2 (Ec-0.39 eV) and El (Ec-0.26 eV) in p-Si. The annealinq of E2 and El are simultaneous with the qrowth of hole traps connected with vacancy (V), Ci and Al.. It is concluded that the observed electronic levels belonq to different charqe states of silicon selfinterstitial . The conclusion is confirmed by the differences of cross sections of the formation of Ali and Ci , by the influence of the zero and reverse bias conditions on the introduction rate and optical annealinq of the E2 state in p-Si as well as by DLTS spectra of n-Si. INTRODUCTION It was established that the selfinterstitial in irradiated p-type silicon is unstable and miqrates even at temperatures 330K, at which the defect is annealed out. Therefore, is suqqested it is not introduced at temperatures -330 K. It that the defect anneals due to the charqe transfer mechanism or due to the saddle point (Bourqoin-Corbett) mechanism. The E2 defect is tentatively attributed to the Si*/Si** donor state. 1

1

EXPERIMENTAL RESULTS Our previous data [3] allowed us to suppose that E2 state belonq to positively charqe center Si 1 . The annealinq of E2 level is simultaneous with the qrowth of H2 (Ci) and H3 (A.i) (fiq. 1). The H3 levels is observed only in irradiated Al-doped [4) state because the material. It is attributed to the A1/A1i 1 1 defect has the same annealinq characteristic and temperature scale position as well as small and temperature dependent holecapture cross section. One can observe the larqe difference bet-

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E2 200 450 T, K Fiqure 1. DLTS spectra of the after p-Si:Al, measured (1) u-irradiation, (2) after the iniection at 250K and (3) after heat treatment at 300 K. 40

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150 T, K

200

Fiqure 2. The modifications of DLTS spectrum of q-irradiated p-Si:B (1) under the near-bandthe qap liqht illumination with fluence of 108 photon/cm2 s durinq 5 s (2) and 20 s (3).

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ween the cross section of the formation of Ali and that of C. (O'Al- 1 0 0 oC). The reason is a Coulomb interaction between Sii and substitional Al1 atom. The attraction between atoms enhanced s

injection of Al1 5 into the interstitial site. The additional data about the properties of E2 defect have been obtained by the studies of low temperature optical iniection annealinq and of the influence of the reverse bias on the introduction rate and annealinq of this state. The five and twenty second optical injection at 175 K introduced the H4 (Ev+0.1 3 eV) state of vacancy, enhanced the formation of H2 (Ci) and sliqhtly decreased the H1 (VV) concentration (fiq. 2). Low temperature o