Effects of Crystallographic Orientation and Strain on Quantum Confined Structures and Devices

摘要

The majority of the heterostructures grown by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) over the last thirty years have been grown on substrates oriented in the 001 crystallographic direction. By comparison, there has been very little work on growth on other crystallographic axes or on applications of such structures. However, theoretical considerations (and several recent experiments) would indicate that unique and useful properties can be realized by growth in other directions. For example, the effective mass, the optical matrix elements, nonlinear susceptibilities, piezoelectric effects and the effects of strain and of confinement are all expected to depend upon crystallographic direction. In addition, it is expected that the application of an external strain or the application an intense optical field will induce similar anisotropies in the optical properties of conventionally oriented materials. Here, we proposed to continue a fundamental investigation of the unique optical and optoelectronic properties of 110, 111 and 1 12-oriented multiple quantum wells (MQWs) and of the optical anisotropies that could be introduced by strain and optical excitation in conventionally oriented materials. The latter should be particularly useful in, for example, constructing high-speed high-contrast spatial light modulators.