The Impact Of Strained Layers On Current And Emerging Semiconductor Laser Systems

In this paper, we discuss how the deliberate and controlled introduction of strain can be used to improve the performance of semiconductor lasers. We show how strain-induced modifications of the electronic band structure give rise to significant changes in the valence band of III-V semiconductors which have been used to produce devices with lower threshold currents and higher efficiencies. We furthermore illustrate how the strain limit of semiconductor layers can be overcome by using strain compensation techniques and how this is being widely adopted in lasers based on a number of emerging III-V systems, enhancing device efficiency and output power and extending the wavelength of operation. We show how strained layers are also being used to optimize the performance of mid-infrared lasers through band offset control. Finally, we show how strain may be used to facilitate the production of lasers on silicon through controlling the conduction band valley splitting in group IV semiconductors or through the development of novel direct bandgap III-V systems that may be grown lattice matched to silicon. Such systems are expected to be of significant potential for the future convergence of electronic and photonic devices and highlight the ongoing importance of strain engineering in photonic devices.