Temperature and strain dependence of the roughening transition in III-V semiconductor and SiGe epitaxial growth

Experimental and theoretical evidence is given for the occurrence of a temperature and strain dependent roughening transition from two dimensional (2-D) monolayer to 3-D island growth in strained III-V compound ternary alloys and GeSi. For sufficiently large strain energy values the shape of the transition curve was found to follow a T∼ε^-2_f relationship, as predicted from classical nucleation theory arguments, where T is the growth temperature and ε_f the areal misfit strain energy. The asymptotic behavior in the zero strain energy regime could be reproduced by an empirical curve of a more complex expression. The transition curve appears to separate routes of strain relief in the above systems, which were found to predominantly follow 3-D island formation in the higher, and misfit dislocation formation in the lower growth temperature/strain regime.