Surface micromorphology of germanium single-crystal boules grown from melt

Abstract

The morphology of the growth surface of germanium single crystals grown by directed crystalliza tion and the Czochralski method is studied by interference profilometry, optical microscopy, and scanning electron microscopy (SEM). Stable periodic profile distributions on different time scales (~3 and ~0.3 s) indicating changes in the crystallization kinetics are revealed on the upper surface of disks grown by directed crystallization and the lateral cylindrical surface of Czochralski pulled boules. Based on known data on temper ature fluctuations at the crystal-melt interface and the parameters of the crystal's surface profile and growth rates measured in this study, the kinetic coefficients are estimated to be β K = (2 × 10 -6 -7 × 10 -7 ) m s -1 K -1 . The two dimensional pattern of irregularity distribution on the surfaces indicates the stepwise growth of the {111} singular faces according to the layer by layer mechanism. A correlation between profile irregularities and periodicity in the distribution of dislocation etch pits over the radius and lateral crystal surface is revealed on juvenile crystal surfaces.

Modification of a Germanium Surface Exposed to Radiation of a Nanosecond Ultraviolet Laser

“…При росте монокристалла формирование структуры поверхности происходит за счет послойного (тангенциального) роста на ступенях сингулярной грани [50]. При абляции германия наблюдается обратный процесс.…”

“…Глубина формирования измененного слоя составляет менее 10-15 мкм. Скорость формирования плоских граней в ямках составила ∼0,1-0,3 м/с, что на несколько порядков превышает скорость формирования граней при росте кристалла [50,51].…”