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Home Azerbaijan Technologies Growth of Uniform Ge-Si Solid Solution Single Crystals by the Modified Bridgman Method Using a Ge Seed

Growth of Uniform Ge-Si Solid Solution Single Crystals by the Modified Bridgman Method Using a Ge Seed

Description

A modified technique for the growth of Ge-rich Ge-Si single crystals is developed on the basis of the vertical Bridgman method using a Ge seed and a Si source rod. Single crystals were grown in two stages (Fig.1.). In the first stage, a Si source rod was partially immersed in the Ge melt above the seed. A gradual increase in the Si content in the melt leads to constitutional supercooling at the crystallization front and to the growth of an inhomogeneous Ge-Si buffer single crystal. The first stage ends when the temperature at the crystallization front becomes equal to the liquid’s temperature of the specified composition of the Ge-Si system. In the second stage, a homogeneous Ge-Si single crystal is grown while maintaining a constant growth temperature. The growth temperature is controlled by an appropriate balance between the pulling and feeding rates. Relations determining the optimal process parameters (the pulling and feeding rates and the temperature gradient at the crystallization front) for growing crystals of specified composition are obtained.

Innovative Aspect and Main Advantages

Growth of Ge-Si single crystals with desired graded and uniform compositions without using adequate solid solutions seed rods.

Areas of Application

The potential application include optoelectronic devices, thermoelectric power generation, intrinsic and extrinsic photo detectors, solar cells, substrate for epitaxial growth techniques.


Fig. 1 Temperature distribution in the heater (left) and the
schematic diagram of the growth of homogeneous GeSi single
crystals (right): (A) starting point, (B) stage 1 (growth of a buffer
crystal of variable composition on a Ge seed), and (C) stage 2
(growth of a homogeneous GeSi crystal on the buffer crystal)


Fig. 2 Calculated distributions of Si along the three Ge-Si ingots
grown in two stages to obtain crystals with a Si content of 10, 20
and 30 at.% in the homogeneous part. The calculations assumed
that the melt height at the starting point is 100 mm and the temperature
gradient in the growth zone of the buffer crystal is 50K/cm.

Stage of Development

Laboratory tested technology for preparation of uniform Ge- Si single crystals with silicon content up to 15 %.

Contact Details

Institute of Physics
Contact person: Azhdarov Gusnu Khalil
Address: 33, H. Javid Avenue, AZ1143, Baku, Azerbaijan
Tel: (+994 12) 438 4503
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

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