PT04. III-V Compound semiconductors based quantum structures for IR detection

Long-wavelength infrared (LWIR) detectors are important in many different applications such as space surveillance systems, low-background infrared seeker-tracker systems, remote environmental monitoring, remote analysis of gases in outer space, and remote temperature measurement. One primary concern with producing LWIR detectors is that they must be made with a material having an energy band gap small enough to allow electrons to be excited from the valence band to the conduction band by the infrared radiation. However, the lowest band gap of the III-V material family is InSb (Eg= 0.174 eV @ 300 K), which corresponds to a wavelength of about 7.1 μm. This makes it difficult to fabricate a long-wavelength (8-14 μm) detector from a bulk III-V material. One way to approach is to make use of quantum wells (QWs) grown in the III-V material family. A QW is made when a thin layer of small band gap material is sandwiched between materials that have a higher band gap. This higher band gap material is called the barrier, where as the lower band gap material is called the well. If the well is thin enough and deep enough, then instead of a continuum of allowed states like those in the conduction band of a bulk semiconductor, a few discrete states are formed in the well. The number of discrete states that are formed depend on the physical and material properties of the well and barrier. Present talk deals with the development of Quantum wells and Dots of GaAs for efficient IR detection.