ABSTRACT
One of the most common and yet an important issue in thin fi lms is the persistence of stress aft er the fi lm growth, which is termed as the internal residual stress. Although the attempt to measure and understand the stress in fi lms started as early as 1877 [1], the topic continues to be interesting and important even today with various innovative analyses and measurement techniques. A few early authoritative reviews [2,3] on this topic have been excellent sources of information, which has assisted in the further growth of knowledge. Th e residual stress depends on various factors like the method of growth, growth parameters, nature of substrates, and starting material and then aft er growth fi lm processing, etc. Development of stress in fi lms could be both advantageous and disadvantageous. A very well-known, advantageous eff ect is the formation of self-assembled quantum dots in heteroepitaxial growths caused by the development of stress due to the lattice mismatch between fi lm and the substrate [4,5]. Th us, the quantum dot growth can be tailored or controlled in a desirable way by a proper choice of the extent of fi lmsubstrate lattice mismatch. Th is has already led to the successful development of various devices based on quantum dots. However, residual stress may be quite undesirable and disadvantageous in the fabrication of almost all other planar thin fi lm electronic devices as it could lead to failure of the device, or else can modify the device performance undesirably, e.g., micro electronic or microelectromechanical systems (MEMS). Subsequently, the study of the residual stress eff ect and its elimination or minimization becomes necessary for such applications. Most of the properties of the materials are aff ected by the stress, either externally applied or the internal residual stress. Th erefore, the study of the residual stress eff ect in thin fi lms could be analogous to the externally applied pressure eff ect. Th is fact facilitates the
possibility of studying the pressure-dependent physical properties without any actual externally applied high-pressure experiments. As the band structure depends crucially on the structure, the electronic properties of the semiconductors can be expected to exhibit interesting stress-strain dependence. Th e study of residual stress therefore seems to be of signifi cant importance, although the fundamental mechanisms for its origin are far from being fully understood. Th erefore, I will try to present the necessary and suffi cient information on the topic in this limited review.
