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T h e process of single crystal pulling is considered with siniultaneous st,arting iimterial make-up into t h e melt and heater temperature control in response to a signal generated 1)y t h e electronic contact melt level sensor, viz. : (i) conditions ensuring t h e radial broadening steadiness; (ii) effect of melt level displacernent, inelt ternperatlire changes, changes of solitl/liqiiid interface shape, melt evaporation on t h e growing crystal dittrneter; (iii) conditions of crystal purification from impurities and uniform tlistrilmtion of dopant.

The behaviour of crystallization rate and interface position under the change of Czocliralslii growth system parameters is theoretically and experimentally investigated for the case of large diameter crystals growth. It is shown that the large value of crystal diameter leads to the inertia and nonmonotonic character of system relaxation after the perturbation. The possibility of hesitative nonstability is discussed. The growth of perfect single crystals doesn't only require a careful choice of the growth regime, but a thorough maintaining of selected regime as well. An accidental change of growth system parameters and inadequate operation lead to fluctuations of crystallization rate. The crystallization rate v is one of the most important growth parameters, its fluctuations are the basic reason of inhomogeneities emergence in the growing crystal. That's why the effect of Czochralski system parameters change on the crystallization rate is discussed in the present paper.The transient regimes during the growth are determined by the relaxation processes, connected with the shift of the interface from the equilibrium position. The most intense relaxation realizes due t o the change of temperature gradient in liquid phase because of the change of thermal boundary layer thickness h. The liquid phase relaxation time tL equals ( HANGLEITER, SPAETH ; LEYBOVICH, POGODIN)Here 6H is the change of interface position, 6v is the change of the crystallization rate, L is the latent heat of crystallization, GL is the stationary value of temperature gradient in liquid phase a t the interface, AL is the melt thermoconductivity.The relaxation (1) affects on the crystallization rate with the delay h2 XL T L = e ,where xL is the melt temperature conductivity.

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