chapter  34
16 Pages

Quantum Dot Infrared Photodetectors and Focal Plane Arrays

Quantum dots (QDs) are semiconductor nanocrystallites that have dimensions smaller than the de Broglie wavelength of electrons in semiconductors [1,2]. ™ere are generally two size groups of quantum dots obtained from di£erent methods. ™e šrst is colloidal QDs such as CdSe and PbS [3-5]. ™e colloidal QDs can be synthesized in various sizes and forms and can also be combined with conductive polymers. ™e colloidal QDs have a dimension of 3-5nm diameter. ™eir working wavelengths (emission or absorption) are in visible or near infrared (IR) regions. ™e second type is epitaxial QDs such as InAs. Epitaxial QDs are self-assembled nanocrystallites grown by molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD) through the Stranski-Krastanow (S-K) growth mode [6,7]. ™e epitaxial QDs have dimensions of usually ∼20-40nm at the base and are 5-8nm high [2]. ™ey work at near infrared (NIR) through far infrared (FIR) regions. In this chapter, we will be focusing on the inter-subband transition in InAs QDs for LWIR optoelectronic devices.