On the diffusion and activation of n-type dopants in Ge

Diffusion and activation of n-type dopants in Ge are discussed with particular emphasis on shallow junction formation. It is shown that both the increase of dopant diffusivity and the reduced fraction of substitutional dopant with increasing dopant concentration are determined by (double) negatively...

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Bibliographic Details
Published in:Materials science in semiconductor processing 2012-12, Vol.15 (6), p.642-655
Main Authors: Vanhellemont, Jan, Simoen, Eddy
Format: Article
Language:English
Subjects:
Activation
Donor
Donor diffusion
Donor solubility
Germanium
Point defect engineering
Vacancy
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Summary:Diffusion and activation of n-type dopants in Ge are discussed with particular emphasis on shallow junction formation. It is shown that both the increase of dopant diffusivity and the reduced fraction of substitutional dopant with increasing dopant concentration are determined by (double) negatively charged vacancies pairing with dopant atoms. The results show that P is the best choice donor atom in Ge as the achievable electron concentration is higher and the extrinsic diffusivity lower than that is the case for As and Sb. Possible ways to increase the dopant substitutional solubility and the degree of activation and to reduce extrinsic diffusivity by point defect engineering are also addressed. Co-doping with Sn seems a promising approach to increase the free carrier concentration and to suppress extrinsic donor diffusion.
ISSN:1369-8001
1873-4081
DOI:10.1016/j.mssp.2012.06.014