RU2381305C1 - METHOD OF GROWING GERMANIUM MONOCRYSTALS WITH DIAMETRE OF UP TO 150 mm USING OTF METHOD - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to growing doped germanium monocrystals in a temperature gradient using a heating element immersed in a melt under conditions of an axial heat flow near a crystallisation front (OTF method). The doped germanium monocrystals are grown from a melt in a crucible placed on a heat-removing unit to an crystallographically directed innculant with diametre equal to the inner diametre of the crucible, under conditions of axial heat flow near the crystallisation front - OTF method, using a multi-section background heater and a multi-section immersed in the melt - OTF-heater kept at constant temperature T₁ by moving the crucible with the inoculant and growing crystal into the cold zone of the furnace relative the OTF-heater, with different initial concentrations of doping impurities C₁ in the crystallisation zone W₁ with height of the melt h, and C₂ in a replenishment zone W₂, and with reduction of temperature of the bottom of the crucible T₄(t) when moving, in accordance with the law: T₄(t)=T₄ ⁰ -a×t, where T₄ ⁰ is initial temperature value, a=v(λ_m×gradTp+Q)/λ_cr, v is drawing rate of the crystal, λ_m is thermal conductivity of molten germanium, gradTp is axial temperature gradient in the melt in which the crystal is grown, Q is crystallisation heat, λ_cr is thermal conductivity of the germanium crystal. Mass transfer of the melt is controlled in the crystallisation zone by selecting optimum ratio between axial temperature gradient in the melt gradTp, radial distribution of temperature along the OTF-heater, height of the layer of the melt h and drawing rate v. Germanium monocrystals are grown in crystallographic dirctions [111] and [100] depending on diametre of the crystal and required quality given the following parameters: h=5-30 mm, gradTp=3-50°C/cm, v=2-30 mm/h, temperature difference of the OTF-heater T₂-T₁=0-6°C, temperature difference between the lateral surface of the crucible T₃ and temperature of the OTF-heater T₂, equal to T₃-T₂=1-20°C.

EFFECT: obtaining germanium monocrystals with diametre of up to 150 mm without growth region with high cross sectional macro-uniformity of distribution of resistance of 5-10%.

10 cl, 1 ex, 2 dwg

Description

The invention relates to the growth of single crystals of germanium from a melt in a temperature gradient using a heating element immersed in the melt.

A method is known in which a melt-immersed heater is used to grow germanium crystals (see AGOstrogorsky, HJSell, S. Scharl and G. Muller. Convection and segregation during growth of Ge and InSb crystals by the submerged heater method, Journal of Crystal Growth, 128 (1993) 201-206) [1]. This work uses the SHM immersion heater method (US Pat. No. 5,047,113, C30B 11/02, 1989 [2]). The immersed heater method was developed with the aim of obtaining an axial heat flux, a small radial temperature gradient and a low intensity of the melt flow in order to increase macro- and micro-uniformity, and also to obtain constant thermal conditions during crystal growth. The axial heat flow is achieved by using a heater immersed in the melt simultaneously with an annular heater located outside the crucible coaxially immersed in the heater and playing the role of a security heater [1]. The constancy of the axial temperature gradient is achieved by maintaining the temperature of the heater immersed in the melt. Small radial temperature differences in the melt are achieved by controlling the ring heater. An increase in longitudinal macrohomogeneity was achieved by additional alloying of the melt zone under an immersed heater. As a result of applying the method, germanium single crystals with a diameter of up to 6 cm were obtained, which had the following characteristics: transverse uniformity at the level of 10–20%, the best longitudinal uniformity reached about 5% over a length of 2 cm from 5 cm of the crystal length [1]. Thus, results were obtained showing the promise of SHM compared to the Bridgman method and the gradient freezing method. However, crystals with a diameter of more than 6 cm were not grown by this method.

The following disadvantages limit the use of SHM for producing large-diameter germanium single crystals: 1) maintaining a constant temperature only of the immersed heater does not provide a constant axial temperature gradient in the melt due to the thermal resistance of the melt-crystal system changing as the crystal grows, 2) the use of a single-section immersed heater and ring security heater does not automatically provide temperature distribution under the OTF heater, close to isothermal for a large crystal diameter, and the use of this approach leads to the fact that the shape of the crystallization front depends on the thickness of the melt layer and changes due to a change in the thermal resistance of the system during growth, in addition, due to the action of the heat of crystallization, the shape of the crystallization front depends on growth rates, 3) the high thermal conductivity of the melt (close to the thermal conductivity of graphite) negates the role of a graphite block immersed in the melt instead of a heater (as was done in Journal of Crystal Growth, 128 (1993) 201-206), therefore the radial Differential differences in comparison with the Bridgman method do not decrease when it is used, which becomes even more pronounced with large crystal diameters.

Closest to the claimed method of growing crystals of germanium is the method described in the patent for the invention "Method for growing single crystals of germanium by the OTF method", the authors Bykova SV, Golyshev VD, Gonik MA, Tsvetovsky VB [3]. This work is based on the application of the Axial Heat Flow method near the Crystallization Front, the OTF method (RU No. 1800854, С30В 11/00, 1990 [4]). This method and the method described in [4] are closest to the claimed method for growing large-diameter germanium crystals, since, unlike [1, 2], they use a different principle of creating an axial heat flow, which is more suitable for large-diameter crystals. In accordance with this principle, an axial heat flow is generated only near the crystallization front. For this purpose, a flat isothermal surface is placed along a large part of the cross section of the growing crystal at a small distance from the assumed position of the crystallization front (RU # 1800004, C30B 11/00, 1990 [4]). The axial heat flux and the planar shape of the isotherms (crystallization front) are realized in this case at a distance h from the isothermal surface, where h <0.13D, D is the diameter of the isothermal surface. The immersed heater in the method described in the aforementioned patent for the invention [3] and in the patent of the Russian Federation No. 1800854, СВВ 11/00, 1990 [4], solves the problem of creating the aforementioned flat isothermal surface. Since this proposal uses the same principle of creating an axial heat flux, [3] is chosen as the closest analogue.

The disadvantages of the two growing methods described above when they are used to grow large-sized single crystals are related to the fact that they are mainly focused on creating the required thermal conditions of crystallization and do not take into account the influence of crystallization parameters and increasing diameter of a growing crystal on mass transfer near the crystallization front. At the same time, the role of size for methods using an immersed heater is significant due to the fact that the scale factor strongly affects mass transfer under conditions of weak laminar flow near the crystallization front. Even with relatively small crystal diameters for these methods, it is necessary to monitor the relationship between the intensity and nature of thermal convection and the intensity of mass release near the crystallization front due to segregation [5, 6] and choose the optimal ratio of crystallization parameters. With increasing diameter, its role greatly increases due to the fact that the geometry of the melt layer under an immersed heater turns into the geometry of a long horizontal gap with heating from above.

EFFECT: growing single crystals of germanium with a diameter of up to 6 inches, having a macrohomogeneous distribution of the dopant at the level of 1-10%.

EFFECT: growing doped germanium single crystals from a melt in a crucible placed on a heat sink block onto a crystallographically oriented seed with a diameter equal to the inner diameter of the crucible under axial heat flux near the crystallization front using the OTF method using a multisection background heater and a multisection immersed in the melt heater - OTF heater maintained at a constant temperature T _1, by moving the crucible with seeding and growing cristae llom in the cold zone of the furnace relatively OTF-heater, at different initial concentration of dopant C ₁ W ₁ crystallization zone, with h and C ₁ melt height in feeding zone W ₂ and decreasing in the course of moving the crucible bottom temperature of crucible T ₄ (t ) in accordance with the law: T ₄ (t) = T ₄ ° -a × t, where T ₄ , K is the initial temperature value; a = v (λ _p × gradTp + Q) / λ _cr , v, m / s is the speed of drawing the crystal; λ _p , Bm / (m × K) is the thermal conductivity of the germanium melt; gradTp, K / m - axial temperature gradient in the melt at which the crystal is grown, Q = ρ × v × J, ρ, kg / m ³ - germanium density; J, j / kg — specific heat of crystallization; λ _cr , Bm / (m × K) - the thermal conductivity of a germanium crystal is achieved by controlling the transfer of melt mass in the crystallization zone that is uniformly doped with germanium single crystals with a diameter of up to 150 mm, which is achieved by choosing the optimal ratio between the axial gradient temperature in the melt gradTp, the radial temperature distribution along the OTP heater, the height of the melt layer h and the drawing speed v, while the growth of single crystals of germanium in crystallographic directions [ 111] and [100] are depending on the diameter of the crystal and the required quality with the following parameters: h = 5-30 mm, gradTp = 3-50 ° C / cm, ν = 2-30 mm / h, temperature difference of the OTP heater T ₂ -T ₁ = 0-6 ° C, the temperature difference between the side surface of the crucible T ₃ and the temperature of the TFT heater T ₂ equal to

T ₃ -T ₂ = 1-20 ° C.

In particular, to realize the growth of germanium single crystals with a diameter of up to 150 mm, the charge is loaded in two stages: first, the OTP heater is placed on the seed, and then the mixture is placed on top of the OTP heater.

In particular, to fix the beginning of the melting of the seed, the beginning of the movement of the OTP heater along the vertical axis is controlled.

In particular, to fix the onset of melting of the seeds, the force exerted by the OTP heater on the weight or pressure sensor is monitored.

In particular, the growth of germanium single crystals with a diameter of up to 150 mm, doped with antimony and gallium, is carried out by maintaining the given time dependences of the temperature or power of the sections of the background heater Th ₁ -Th ₄ using an automatic control system.

In particular, the growth of single crystals of germanium is carried out with a change in temperature Th ₁ -Th ₄ in accordance with the following laws: Th ₁ (t) = Th ₁ (0) + a ₁ t, Th ₂ (t) = Th ₂ (0) + a ₂ t, Th ₃ (t) = Th ₃ (0) + a ₃ t, Th ₄ (t) = Th ₄ (0) + a ₄ t, where a ₁ = 0 ÷ (± 3ν × gradT), a ₂ = 0 ÷ (± 3ν × gradT), a ₃ = 0 ÷ (± νgradT), a ₄ = 0 ÷ (± vgradT), t, s - time in the process; gradT, K / m - axial temperature gradient in the furnace; ν, m / s is the crucible pulling speed; Th _1-4 (0), K - initial temperature values.

In particular, the growth of single crystals of germanium doped with antimony and gallium is carried out when the temperature or power of the sections of the OTP heater is changed.

In particular, the growth of single crystals of germanium is carried out with a change in T ₁ in accordance with the law: T ₁ = T ₁ (0) + bt, where T ₁ (0), K is the initial temperature; t, s is the time in the process, b = + nν, ν, m / s is the drawing speed, n is selected based on the diameter of the crystal and the initial conditions formed during the seeding.

In particular, the growth of germanium single crystals is carried out with an increase in the total power of the sections of the OTP heater in accordance with an increase in the radius of the crystal, including in proportion to the square of the radius of the crystal.

In particular, to remove heat from the bottom of the crucible, a heat sink block is used, the diameter of which is in the range 0.2-1.0 of the diameter of the crucible.

The technical result due to the use of a heater immersed in the melt by using the technique of OTF-growth of germanium crystals with a diameter of up to 150 mm is achieved by the method illustrated in Fig. 1, where Fig. 1a shows a conditional diagram of a crystallizer at the time of growing a crystal, Fig. 1b shows a conditional diagram a growth chamber with a crystallizer after loading the charge, 1 — single-crystal seed, 2 — crucible, 3 — molten germanium, 4 — OTF-heater, 5 — growing crystal, 6 — body of the growth chamber, 7 — charge in the form of bars or in in the form of small pieces of polycrystalline germanium, 8 - a displacement or weight or pressure sensor, 9 - a heat sink unit, 10 - insulation, 11 - an OTF heater rod, 12 - a water-cooled crucible rod, T1-T4 - crystallizer thermocouples, Th1-Th4 - thermocouples sections of the background heater, Hc and Hb are the central and side sections of the OTF heater, H1-H4 are sections of the background heater, W1 and W2 are the crystallization zone and the make-up zone.

The growth of germanium crystals is carried out by seed 1 with a diameter equal to the inner diameter of the crucible in crucible 2 made of a material not interacting with melt 3 using a two-section heater 4 immersed in the melt (OTP heater) consisting of a central Hc section and a side Hb section (Fig. .1a), by moving the crucible with the seed and the growing crystal 5 (Fig.1a) into the cold zone of the furnace relative to the growth chamber 6 fixed in the housing of the growth chamber 6 by means of the rod 11 (Fig.1b) of an OTF heater maintained at a constant temperature T ₁ , and using shuya separate alloying of zones W ₁ and W ₂ (figa). In contrast to the known methods [1, 3], in order to obtain growing germanium single crystals evenly doped over most of the cross section with a diameter of up to 150 mm, mass transfer in the crystallization zone W _{1 is} controlled by choosing the optimal ratio between the axial temperature gradient in the gradTp melt radial the temperature distribution along the OTP heater, the height of the melt layer h and the drawing speed ν.

This method is associated with the fact that the macroinhomogeneity of the crystal in the cross section for methods using an immersed heater depends on the intensity and nature of the melt flow in the crystallization zone [5–8] in relation to the growth rate. The intensity and nature of the melt flow depends on the height of the melt layer h in the crystallization zone (Fig. 1a), on the radial temperature distribution on the OTP heater, on the axial temperature gradient in the melt and on the shape of the crystallization front. Figure 2 shows how the nature of the transverse distribution of the dopant, Sb (experimental data — the upper row of the drawings) changes when the nature of the flow (numerical simulation — the lower row of the drawings) changes due to a change in the height of the melt layer h, where 2a is the flow from the center; 2b — two vortices; 2c — flow toward the center, n — concentration of the dopant, r — radius of the crystal. With increasing diameter of the growing crystal, i.e. the diameter of the melt zone in the crystallization zone W1, the driving forces of thermal convection change. Therefore, in order to obtain high transverse macro-uniformity of a larger single crystal, the combination between the growth rate, melt layer thickness h and the radial temperature distribution on an OTP heater is significantly different than that used in [3] for small crystal diameters. In addition, in the case of growing large-sized crystals, both thermal inertia and the alignment time after perturbation of mass transfer processes are significantly longer. This leads to the following differences compared to [3].

In contrast to [3], in the proposed method for growing germanium, the charge is loaded in two stages: first, the OTP heater is placed on the seed 1, and then the mixture 7 is placed on top of the OTP heater 4 (Fig. 1b). This is done so that, in contrast to [3], in the proposed method for growing germanium at the beginning of the growing process, the experimental control of the thickness of the melt layer h should not be performed by measuring the displacement of the OTP heater to its contact with the interface, which leads to process disturbance mass transfer. Thus, in the proposed method, in contrast to [3], the procedure for fixing the start of seed melting is used, which is controlled either by the beginning of movement along the vertical axis of the OTF heater standing on the seed, or by changing the force exerted by the OTF heater through the rod 11 to the sensor weight or pressure 8 (figb).

In contrast to [3] in the proposed method for growing germanium, the constancy of the thermal conditions of crystallization during growth is achieved not by maintaining the temperatures T ₁ , T ₂ and T ₃ and changing the temperature at point T ₄ (Fig. 1a), but by maintaining the set time dependences of temperatures Th ₁ -Th ₄ (or power) of the background heater sections H1-H4 (Fig. 1b) using an automatic control system. This is due to the fact that micro- and macrohomogeneity in weak laminar melt flows depends on the amplitude and frequency of temperature fluctuations of an OTP heater due to its proximity to the crystallization front and on the amplitude and frequency of temperature fluctuations of the crucible walls, since these vibrations affect on the driving forces of thermal convection, and therefore, on the flow of the melt. With large sizes (diameters) of the crystal and, accordingly, of the thermal unit, thermal inertia increases many times, which leads to the fact that high-precision temperature control by thermocouples T ₁ , T ₂ , T ₃ and T ₄ located on the mold becomes problematic. At the same time, control over the thermocouples Th ₁ -Th ₄ located near the heating elements is characterized by relatively low thermal inertia and higher quality. However, the problem is that with this control method in order to provide the necessary combination of crystallization parameters (axial temperature gradient gradTp in the melt, radial temperature distribution along the OTP heater, melt layer height h and drawing speed ν), which give a uniform distribution of the dopant and maintain them constant during the growth process, it is necessary for special laws manage Th ₁ -Th ₄ temperatures, as during crystal growth changes the thermal conditions in the crystallization zone (axial and adialnye temperature gradients in the melt) due to a change in thermal resistance, including the crystal-melt system. For example, in a real thermal unit intended for growing 6-inch crystals, depending on the crystal growing conditions, the thermal resistance in the axial direction varies from 1.2 to 1.5 times.

Therefore, in contrast to [3], in the proposed method for growing germanium, depending on the size of the crystal, its required quality and the initial value of the thickness of the melt layer in the crystallization zone h, the crystallization process is carried out with a change in temperature Th ₁ -Th ₄ , K, in accordance with the following laws : T _h1 (t) = T _h1 (0) + a ₁ t, T _h2 (t) = T _h2 (0) + a ₂ t, Th ₃ (t) = Th ₃ (0) + a ₃ t, Th ₄ (t) = Th ₄ (0) + a ₄ t, where a ₁ = 0 ÷ (± 3ν × gradT), a ₂ = 0 ÷ (± 3ν × gradT), a ₃ = 0 ÷ (± νgradT), a ₄ = 0 ÷ (± νgradT), t, s - time in the process; gradT, K / m - axial temperature gradient in the furnace; ν, m / s is the crucible pulling speed; Th _1-4 (0), K - initial temperature values.

The growth of single crystals of germanium with a diameter of up to 150 mm, doped with antimony and gallium, in contrast to [3], is carried out with a change in temperature (power) of the sections of the OTP heater. This control method is due to the high sensitivity of the nature of the distribution of the dopant to the thickness of the melt layer (Fig. 3) and is also associated with a change in the axial direction of the heat resistance during heat growth. Compensation for the effect of changes in thermal resistance is carried out in two ways. According to the first method, Th ₁ , Th ₂ decrease according to the law Th ₁ (t) = Th ₁ (0) -a ₁ t, Th ₂ (t) = Th ₂ (0) -a ₂ t in order to maintain the axial thermal value flow through the melt and maintain an axial temperature gradient in the melt. According to the second method, the total power released by the OTP heater increases, T ₁ increases, and the power ratio between the sections of the OTP heater changes to maintain the radial temperature gradient.

Moreover, in contrast to [3], in order to control the melt flow and compensate for the influence of the flow change due to a change in the shape of the crystallization front due to a change in thermal resistance in the system, the growth of germanium single crystals is carried out with a change in T ₁ in accordance with the law: T ₁ = T ₁ (0) ± bt, where T ₁ (0), K is the initial temperature value; t, s - time in the process; b is nν; v, m / s - pulling speed; n - is selected on the basis of numerical simulation and experiment, depending on the diameter of the crystal and the initial conditions formed by the seed, necessary to obtain the desired quality.

In contrast to [3], the total power of the sections of the OTP heater increases with increasing radius of the crystal, including in proportion to the square of the radius of the crystal.

In addition, in contrast to [3], the heat sink through the growing crystal is also controlled by selecting the diameter of the heat sink block 9 (Fig. 1b), which is selected in the range 0.2-1.0 of the diameter of the crucible in order to obtain optimal heat removal from the bottom of the crucible with the growing crystal . This is also necessary due to the fact that with a large crystal diameter, an increase in the reliability of the seeding process is required, since with increasing mass-dimensional characteristics of the system, the inertia of thermal processes increases.

After placing the charge over the OTP heater, the furnace chamber closes and the installation is heated. The charge is melted by the temperature distribution in the furnace above the OTF heater. Seeding occurs by melting the seed with an increase in the temperature of the bottom of the OTP heater above the melting temperature of germanium. The appearance of the melt under the OTF heater is characterized by a change in the force (load) on the rod on which the OTF heater is mounted, and its displacement along the vertical axis. This change in the force or position of the OTP heater is detected by the corresponding sensor 8 by means of the rod 11 (Fig. 1b). Thus, the start of the seeding process is controlled independently of temperature measurements. The initial installation of the OTF heater on the seed and the control of the seeding process independent of temperature measurements significantly facilitate and increase the reliability of the seeding process. This is especially important when working in small temperature gradients, since the instrumental error of the thermocouples used can reach five degrees, which, when the temperature gradient is 5 degrees / cm, will give an error in estimating the thickness of the melt layer under the OTF heater of 1 cm. This is comparable to the thickness of the used seed crystals and threatens the complete melting of the seed crystal.

A specific example of growing Ge crystals: The growth of Ge single crystals in the [100] direction with a diameter of 100 mm doped with Sb to a concentration of 5 × 10 ¹⁷ .

The seed from a Ge single crystal is made in the form of a disk with a diameter of 100 mm and a height of 15-20 mm. The seed is placed at the bottom of the graphite crucible. An OTP heater is placed on the seed. On top of the OTP heater, the required amount of Ge charge with a dopant is loaded. The growth chamber is pumped out to a pressure of 10 ^-1 −5 × 10 ⁻² mm Hg. and heat the crucible with the mixture to a temperature of 300-400 ° C to remove moisture and water vapor. Then argon is introduced into the chamber, creating an overpressure of 0.5 atm. An increase in the temperature in the growth chamber above the melting point of germanium in the region above the location of the seed melts the germanium charge. In this case, the axial temperature gradient is kept constant. Next, the seed is melted on top by several millimeters, controlling the beginning of penetration by force on the rod on which the OTP heater is mounted, or by its movement. By varying the power of the background sections and the sections of the OTP heater, the initial values of the temperature of the OTP heater, the radial temperature difference on the OTP heater, the axial temperature gradient in the furnace are set, setting the initial shape of the crystallization front, the thickness of the melt layer and the nature of mass transfer in the melt. After holding for one hour, crystallization begins, lowering the crucible with the crystal down into the cold zone with a drawing speed of 8 mm / hour. Crystallization is carried out in an axial temperature gradient in the furnace equal to 5 ° C / cm, maintaining by the program change in temperature (power) of the sections of the background heater the values of Th _1-4 (t), ° C in accordance with the laws: Th ₁ (t) = Th ₁ (0) + a ₁ t, Th ₂ (t) = Th ₂ (0) + a ₂ t, Th ₃ (t) = Th ₃ (0) + a ₃ t, Th ₄ (t) = Th ₄ ( 0) + a ₄ t, where t, hour - time; a ₁ = -1.8 ° C / hour, a ₂ = -1.8 ° C / hour,

a ₃ = 0, a ₄ = 0. In this case, the temperature of the OTP heater is maintained in accordance with the law: T ₁ = T ₁ (0) + bt, where b = 0.

After crystallization is complete, the temperature in the furnace is slowly reduced at a rate of 50 K / h to a temperature of 400-500 degrees. Then the heaters are turned off and the furnace cools naturally. The grown crystal is removed from the crucible.

As a result, germanium single crystals with a diameter of 100 mm were obtained, having a scatter of transverse inhomogeneity in the distribution of resistance at the level of 5-10%. The percentage of yield from one cycle is 80%.

Information sources

1. A. Ostrogorsky, H. J. Sell, S. Scharl and G. Muller. Convection and segregation during growth of Ge and InSb crystals by the submerged heater method. Journal of Crystal Growth, 128 (1993) 201-206.

2. The method of directional crystallization of single crystals, patent US 5047113 C30B 11/02, 1989.

3. Patent on application No. 2006119535/15 (021235) "Method for growing germanium single crystals by the OTF method", authors Bykova SV, Golyshev VD, Gonik MA, Tsvetovsky VB

4. Device for growing crystals, RF patent No. 1800004, C30B 11/00, 1990.

5. S.V. Bykova, I.V. Frjazinov, V. D. Golyshev, M. A. Gonik, M. P. Marchenko, V. B. Tsvetovsky. Features of mass transfer for the laminar melt flow along the interface. J. Crystal Growth, 2002, vols. 237-239, pp. 1886-1891.

6. M.P. Marchenko, I.V. Fryazinov, V. D. Golyshev, M. A. Gonik, V. B. Tsvetovsky. Numerical simulation of growing single crystals by the OTF1-method under microgravity // Physics of crystallization. By the centenary of G.G. Lemlein. - M.: Publishing House of Physical and Mathematical Literature, 2002. - S.304-316.

7. V.D. Golyshev, M.P. Marchenko, I.V. Frjasinov. Influence of the boundary temperature conditions on the shape of the phase interface, on melt flow and dopant distribution in single crystals grown by the AHP method. Proceeding of the 4th Int. Conference on single crystal growth and heat & mass transfer, Obninsk, Russia, 24-28 September, 2001, Vol. 3, p. 715-724.

8. S.V. Bykova, V. D. Golyshev, M. A. Gonik, V. B. Tsvetovsky, E. Balikci, A. Deal, R. Abbaschian, M. P. Marchenko, Igor. V. Frjazinov, V. N. Vlasov. The experimental-numerical investigation of instability of faceted geopedoped by Sb growth on the base of AHP method. Journal of Crystal Growth, 275 (2005), 229-236.

Claims (10)

1. A method of growing doped germanium single crystals from a melt in a crucible placed on a heat-removing block onto a crystallographically oriented seed with a diameter equal to the inner diameter of the crucible under axial heat flux near the crystallization front using the OTF method using a multi-section background heater and immersed in the melt multiple stage heater - OTF heater maintained at a constant temperature T _1, by moving the crucible and a seed crystal growing in cold h Well furnace relatively OTF-heater, at different initial concentration of dopant C ₁ in the crystallization zone W ₁ with a height h and C ₂ melt zone Drains W ₂ and decreasing during displacement T ₄ (t) of the crucible bottom temperature of the crucible in accordance with by law: T ₄ (t) = T ₄ ⁰ -a · t, where T ₄ ⁰ is the initial temperature value, a = v (λ _p · gradTp + Q) / λ _cr , v is the crystal drawing speed, λ _p is the thermal conductivity germanium melt, gradTp - axial temperature gradient in the melt in which the crystal is grown, Q - heat of crystallization, λ _cr - thermal conductivity of the crystal n mania, characterized in that in order to obtain germanium single crystals uniformly alloyed in cross section with a diameter of up to 150 mm, the melt mass transfer in the crystallization zone is controlled by selecting the optimal ratio between the axial temperature gradient in the gradTp melt and the radial temperature distribution along the OTP heater , the height of the melt layer h and the drawing speed v, while the growth of single crystals of germanium in the crystallographic directions [111] and [100] is carried out depending on the diameter Stull and desired quality for the following parameters: h = 5-30 mm, gradTp = 3-50 ° C / cm, v = 2-30 mm / h, difference in OTF heater temperature T ₂ -T ₁ = 0-6 ° C , the temperature difference between the side surface of the crucible T ₃ and the temperature of the TFT heater T ₂ equal to T ₃ -T ₂ = 1-20 ° C. 2. The method according to claim 1, characterized in that the charge is loaded in two steps: first, the OTP heater is placed on the seed, and then the mixture is placed on top of the OTP heater. 3. The method according to claim 1, characterized in that to fix the beginning of the melting of the seed control the beginning of the movement of the OTP heater along the vertical axis. 4. The method according to claim 1, characterized in that to fix the onset of melting of the seed, the force exerted by the OTF heater on the weight or pressure sensor is controlled. 5. The method according to claim 1, characterized in that the growth of single crystals of germanium doped with antimony and gallium is carried out by maintaining predetermined time dependences of the temperature or power of the background heater sections Th ₁ -Th ₄ using an automatic control system. 6. The method according to claim 5, characterized in that the growth of single crystals of germanium is carried out with a change in temperature Th ₁ -Th ₄ in accordance with the following laws: Th ₁ (t) = Th ₁ (0) + a ₁ t, Th ₂ (t ) = Th ₂ (0) + a ₂ t, Th ₃ (t) = Th ₃ (0) + a ₃ t, Th ₄ (t) = Th ₄ (0) + a ₄ t, where a ₁ = 0 ÷ (± 3v · gradT), a ₂ = 0 ÷ (± 3v · gradT), and ₃ = 0 ÷ (± vgradT), ₄ = 0 ÷ (± vgradT), t is the time in the process, gradT is the axial temperature gradient in the furnace, v is the crucible pulling speed, Th _1-4 (0) are the initial temperatures. 7. The method according to claim 1, characterized in that the growth of single crystals of germanium doped with antimony and gallium is carried out when the temperature or power of the sections of the OTP heater is changed. 8. The method according to claim 7, characterized in that the growth of single crystals of germanium is carried out with a change in T ₁ in accordance with the law: T ₁ (0) ± bt, where T ₁ (0) is the initial temperature, t is the time in the process, b = nv, v is the drawing speed, n is selected based on the diameter of the crystal and the initial conditions formed during seeding. 9. The method according to claim 1, characterized in that the growth of single crystals of germanium is carried out with an increase in the total power of the sections of the OTP heater in accordance with an increase in the radius of the crystal, including in proportion to the square of the radius of the crystal. 10. The method according to claim 1, characterized in that for the removal of heat from the bottom of the crucible using a heat sink unit, the diameter of which is in the range of 0.2-1.0 from the diameter of the crucible.

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