The basic kinetic and thermodynamic concepts of crystal growth will be revisited in view of recent AFM and interferometric findings . These concepts are as follows : 1 ) The Kossel crystal model that allows only one kink type on the crystal surface . The modern theory is developed overwhelmingly for the Kessel model ; 2 ) Presumption that intensive step fluctuations maintain kink density sufficiently high to allow applicability of Gibbs - Thomson law ; 3 ) Common experience that unlimited step bunching ( morphological instability ) during layer growth from solutions and supercooled melts always takes place if the step flow direction coincides with that of the fluid .