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Home Georgian Technologies Bulk Crystals of Si-Ge Alloys

Bulk Crystals of Si-Ge Alloys


Bulk single crystals and polycrystals of the Si-Ge system alloys have been grown by the Crochralski method. The work is an outcome of a joint effort by F. Tavadze Institute of Metallurgy and Materials Science and I. Vekua Sokhumi Institute of Physics and Technology. These materials are of great interest for practical application in varions apparatus of micro¬electronics and optoelectronics, in thermoelectric power generators, monochromators and detectors of Xray and neutron radiation.

In alloys of Si-Ge system there is possible to change smoothly the width of forbidden gap and crystal lattice parameters by variation of Ge content. This has a great importance for apparatus on the base of Si-Ge alloys operating of the extremal conditions. There have been worked out p- and n- type single crystal alloys of Si1-x-Gex (0≤x≤0.0.5) with a wide range of dopant impurities concentrations, B and As (1*1015–1*1020cm-3). Polycrystalline alloys with content of Ge(0≤x≤0.0.5), doped separately with B and As up to the concentration of ∼1*1020 cm-3 have been grown. Complex doped alloys on the base of Si0.85–Ge0.15, doped with GaP (n-type) and jointly with GaP and B (p-type) have been received; these alloys are characterized with high efficiency of thermal energy conversion to electricity.

Innovative Aspect and Main Advantages

The single crystal alloys are characterized by relatively perfect structure, they have stable electrophysical properties, and their dislocation density is not over than 5*103 cm-2; multicomponent alloys of Si-Ge are characterized by high values of thermoelectric conversion efficiency; their operation is stable in the air conditions at 1000-1300°C.

Areas of Application

Single crystal samples of Si-Ge alloys are applied in photoconductive receiver sets of infrared radiation, semiconductor diodes and triodes operating in the range of elevated temperatures; they can be used in tunnel diodes of powerful transistors as a substrate of multilayer heteroepitaxial structures, in monochromators of X-ray and neutron radiation.

Polycrystalline Si-Ge alloys can be used, in nigh-effective thermoelectric elements, batteries and generators operations in range of high temperatures (1000-1300°C).





Fig. 1. Samples of Si-Ge alloys:
a) Sample Si0.98–Ge0.02: B direction of growing;
b) Sample Si0.98–Ge0.02: As direction of growing;
c) Sample Si0.98–Ge0.02, doped with GaP (2 mol%).

Stage of Development

Commercialization stage; pilot samples are available. At present thermoelectrical converters of power for various purposes are being developed on the base of multicomponent alloys of Si-Ge. For marketing the single and polycrystalline samples of Si-Ge can be offered. It is possible to increase samples diameter up to 45-50 mm, and produce materials of 5-6 kg in a week.

Table 1.Si-Ge crystals properties at the room temperature.

Contact Details

Yuri Nardaya
Organization: Sukhumi Institute of Physics and Technology (SIPT)
Address: 15 Kazbegi Avenue 0160 Tbilisi, Georgia
(+995 32) 33 5520
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

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