Semiconductor strained layers

During the past 25 years (after the growth of the first pseudomorphic GeSi strained layers on Si) we have seen a steady accumulation of new materials and devices with enhanced performance made possible by strain. The past year has been good for strained layers. Until recently, short wavelength (violet to green) and mid-infrared (2–5 μm) regions of the spectrum were not accessible to photonic devices. Short wavelength light emitting diodes and laser diodes have been developed using III—Nitride and II–VI strained layers. Improved mid-infrared lasers, using Sb-based III–V semiconductor strained layers, have also been fabricated. These advances have been possible due to improvements in growth techniques as well as in the modelling and computer simulations of layers compositions and device structures. Full band Monte Carlo simulations of electron transport in strained Si predict very high electron mobilities. Computer simulations show that complementary metal oxide silicon circuits, fabricated with strained layer GeSi transistors will have considerably improved performance. Electronic devices based on GeSi strained layers have shown further improvements in high frequency and high power performance. Many devices based on strained layers are being used in commercial equipment. Advances have been made both in modelling and determining the nonuniform strain, using a Raman technique.