Laser-enhanced diffusion of nitrogen and aluminum dopants in silicon carbide

    Authors

    Z. Tian; N. R. Quick;A. Kar

    Comments

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    Abbreviated Journal Title

    Acta Mater.

    Keywords

    silicon carbide; laser doping; Nd : YAG laser; excimer laser; laser-enhanced diffusion; TEMPERATURE IMPLANTED ALUMINUM; ION-IMPLANTATION; Materials Science, Multidisciplinary; Metallurgy & Metallurgical; Engineering

    Abstract

    The diffusivities of different types of dopant atoms in silicon carbide wafers are generally very low. Nd:YAG and excimer lasers have been used to dope silicon carbide with nitrogen and aluminum, respectively. Mathematical models have been presented for the temperature distributions in the wafers to understand the diffusion mechanisms in the laser doping process. Since the silicon carbide substrate reaches its peritectic temperature (3100 K) at irradiances of 80.6 and 61 MW/cm(2) for Nd:YAG and excimer lasers, respectively, lower irradiances were used to achieve solid-state diffusion. The Nd:YAG laser doping process doped nitrogen to a depth of 800 nm; the KrF excimer laser doping process produced aluminum dopant depths of 200 and 450 nm for different numbers of laser pulses. Two distinct diffusion regions, near-surface and far-surface regions, were identified in the dopant concentration profiles, indicating different diffusion mechanisms in these two regions. The effective diffusion coefficients of nitrogen and aluminum were determined for both regions and found to be 2.4 x 10(-5) and 9.2 x 10(-6) cm(2)/s in the near- and far-surface regions for nitrogen, respectively, and 1.2 x 10(-5) and 1.3 x 10-6 cm(2)/s in the near- and far-surface regions for aluminum, respectively. The calculated diffusivities are at least six orders of magnitude higher than the typical values for nitrogen and aluminum, which indicate that the laser doping process enhances significantly the diffusion of dopants in silicon carbide. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

    Journal Title

    Acta Materialia

    Volume

    54

    Issue/Number

    16

    Publication Date

    1-1-2006

    Document Type

    Article

    Language

    English

    First Page

    4273

    Last Page

    4283

    WOS Identifier

    WOS:000240791900016

    ISSN

    1359-6454

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