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Investigation of the influence of the low melt flow velocity on the macro - and microinhomogeneity of semiconductor single crystals

Objective

The work is devoted to determination of influence of the laminar melt flow of low intensity on formation of macro - and micro-inhomogeneity in growth of compound semiconductors. The goal of the work is to determine laws of mass transfer and inhomogeneity formation under conditions of low melt flow and to find conditions for perfect crystals growth both on Earth and in space.
To make an exactly known field of velocities ahead of the melt-crystal interface, a forced melt flow is used which arises from crystallization by the AHP method. The field of velocities of this flow does not depend on thermal growth conditions. The most part of researches will be related to determination of quantitative analytical model for a forced flow and quantitative numerical model of a transient impurity transfer in crystal growth under conditions of low melt flow and experimental testing of these models. It will be proposed to achieve the accuracy in description of impurity concentration distribution in a grown crystal at a level of 5-10%. The AHP method will be utilized to grow single crystals. The accuracy testing in description of a forced flow is based on flow visualization during NaNO3 crystallization. Ge doped by Sb and Ga will be used as a modelling material for accuracy testing in description of impurity transfer processes when a forced flow with an exactly known field of velocities takes place. Ge doped by Sb and Ga and GaSb doped by In and Te will be used as modelling materials in studies of regularities in macro-inhomogeneity formation under conditions of transient laminar flow.

To vary the flow intensity and behaviour during crystallization, the flow will be used changing from a forced flow to a natural convective one and vice versa, as well as flow transition from characteristic for the AHP method to the flow characteristic for the freezing method in the vertical temperature gradient. The research of regularities in micro-inhomogeneity formation will be carried out on the basis of characterization of Ge, GaSb and GaSb-InSb samples grown by the AHP method under steady state and transient laminar flow conditions.

To characterize samples the following methods will be used: spreading technique, four-point probe technique, Hall, SIMS, Photoluminescence, structural characterization (EDAX, HRXRD). During the analysis of GaSb-InSb growth processes more attention will be paid to the problems of the constitutional super cooling and concentration convection. Actual data on temperature at the boundaries recording be the computer system with a period of 10-30 seconds will be used for computational investigation of conditions concerning the micro-inhomogeneity formation.
As a result of fulfilment of work, the fundamentals of the impurity transfer and macro - and micro-inhomogeneity formation will be determined under low intensity of transient laminar melt flows. The technique will be developed and the recommendations will be given related to realization of space experiments and designing of space equipment. The data will be obtained with respect to growth conditions of more perfect single crystals in both micro-gravity and ground-based experiments.

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Coordinator

Commissariat à l'Energie Atomique

Address

17, Avenue Des Martyrs
38054 Grenoble

France

Administrative Contact

Thierry DUFFAR (Professor)

Participants (3)

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Centre of Thermophysical Researches

Russia

Russian Academy of Sciences

Russia

Universidad Autonoma de Madrid

Spain

Project information

Grant agreement ID: INTAS-1999-01814

  • Start date

    1 May 2000

  • End date

    30 April 2002

Funded under:

IC-INTAS

Coordinated by:

Commissariat à l'Energie Atomique

France