Introduction
A semiconductor superlattice is a periodic crystalline structure built up of two or more alternating semiconductor materials. A semiconductor is a material which has some of the properties of both a conductor and an insulator. When the two materials are combined the resulting structure has many of the properties of the two materials but can also have other unique properties. Superlattices are used in many applications, such as lasers, sensors, and optical amplifiers.
Properties of a Semiconductor Superlattice
A semiconductor superlattice is formed when two different materials are alternated at a microscopic level. The thickness of each layer is on the order of fractions of a nanometer. As each layer is added, a lattice of electronic energy states is created which is referred to as a “superlattice”. As a result of this lattice of energy states, the structure of a superlattice is such that it is optically active and can be used to generate light via a process known as light emission.
In addition to being optically active, the energy states of a semiconductor superlattice can be controlled by means of an external electric field. When an electric field is applied to a superlattice, the electron energy states move, altering the optical properties. This phenomenon is referred to as the Quantum Confinement Effect and is one of the major advantages of semiconductor superlattices over other optoelectronic materials. By controlling the electric field, the optical properties of the superlattice can be modified and tuned.
Applications
Semiconductor superlattices have been used in numerous applications because of the unique properties they possess. One of the most prominent applications of superlattices is the fabrication of lasers. Lasers are optical devices that emit a concentrated beam of light. Superlattices can be used to create lasers of specific spectral frequencies, allowing for the tuning of the laser wavelength. Furthermore, superlattices have also been used in the development of optical amplifiers. These amplifiers are used in optical communications systems, enabling faster transfer of data.
In addition to being used in lasers and amplifiers, superlattices have also been used to create optical sensors. Using a superlattice, researchers have been able to create devices that are capable of detecting biomarkers and other small molecules in biochemical assays. Furthermore, superlattices have been used in medical imaging, allowing for the detection of tumors and lesions in the body.
Conclusion
Semiconductor superlattices are particularly useful for the fabrication of various optoelectronic devices. They are advantageous over other optoelectronic materials due to their ability to be tuned using an external electric field. Furthermore, superlattices can be used for the fabrication of lasers, amplifiers and sensors, making them a valuable technological tool.
