The Surfactant Effect in Semiconductor Thin-Film Growth

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This chapter discusses the effect of overlayers, commonly referred to as “surfactants,” on the epitaxial growth of semiconductors. Such overlayers make it possible to lower substantially the temperature required for growth of perfect epitaxial films. As device dimensions decrease, processing temperatures must be lowered to minimize diffusional broadening of interfaces and dopant profiles. Surfactants have been used to modify the growth mode of several systems, including metal layers in homoepitaxy and heteroepitaxy. The chapter also presents several theoretical models that explain the surfactant effect in semiconductor growth. These models may be divided into three categories. The first category comprises of models that concentrate on the microscopic aspects, attempting to understand the atomic-scale features and processes involved in this phenomenon. The second category comprises of models that are more concerned with the macroscopic aspects of the surfactant effect, such as island morphologies, distributions, and the effects of strain, without attempting to explain the details of the atomistic processes. The third category comprises of the models that attempt to combine both aspects (microscopic aspects and macroscopic aspects)—that is, they try to use realistic descriptions of the atomistic processes as the basis for macroscopic models.