Heterostructures Ge xSi 1−x/Si(0 0 1) grown by low-temperature (300–400 °C) molecular beam epitaxy: Misfit dislocation propagation

Abstract

In previous publications [ Tuppen and Gibbings, J. Appl. Phys. 68 (1990) 1526; Hull et al., J. Appl. Phys. 70 (1991) 2052; Houghton, J. Appl. Phys. 70 (1991) 2136], the glide velocity of dislocations was analyzed and estimated in GeSi/Si (0 0 1) heterostructures grown at a temperature of 550 °C. The method of growing GeSi films with the use of a low-temperature Si buffer has been developed recently and was not involved in these studies. The present work deals with a more detailed analysis of dislocation propagation velocities in GeSi films grown with the use of the low-temperature Si buffer and those grown at low-temperatures. The dislocation velocity is estimated by the measuring of the length of misfit dislocations observed in annealed films. Additionally a method for estimating the mean threading dislocation glide velocity is used, which involves the measured threading dislocation density in a particular film and degree of its plastic relaxation directly related to the number of threading dislocations and their glide velocity. It is shown that dislocation glide velocities in heterostructures grown with the use of the low-temperature Si buffer and at low-temperatures are higher than the values predicted by the classical calculations by an order of magnitude.