Impact of Strain on the Electronic and Optoelectronic Properties of III-Nitride Semiconductor Heterostructures

Abstract

III-nitride materials are technologically important material for optoelectronic devices, due to the direct bandgap and tunability of composition over a wide wavelength region (200–700 nm). In addition, III-nitride-based transistors, e.g., high electron mobility transistors (HEMT) have recently paved their way towards application for high-frequency (RF) and high-power devices. The unavailability of large-area III-nitride substrates leads to employing heteroepitaxial growth on foreign substrates. Lattice mismatch with substrates such as Sapphire, SiC, Si causes mechanical strain in the growing layer. Accumulated strain in heteroepitaxial growth can result in non-radiative dislocations in structure, thus lower efficiency in light-emitting diodes (LEDs). Another negative effect of strain in quantum wells (QWs) is compositional pulling, attempting to minimize the incorporation of indium/aluminum in GaN during heteroepitaxial growth. In this chapter, the origin of strain and its impact on mechanical and electrical properties of III-Nitrides are discussed from the perspective of epitaxial thin-film growth.