Semiconductor is a Fortune 500 semiconductors supplier company. Such disordered materials lack the rigid crystalline structure of conventional semiconductors such as silicon. For a comprehensive list of band gaps in semiconductors, see List of semiconductor materials. There are important differences between the processing of small molecule organic semiconductors and semiconducting polymers. Quantum dots have properties intermediate between bulk semiconductors and discrete atoms or molecules. It also has direct applications, for example in the technology of transistors and semiconductors. Cold emission of electrons is relevant to semiconductors and superconductor physics. Several companies specialize in manufacturing power semiconductors. The field studies metals, ceramics, glass, plastics, semiconductors, and composite materials. The product portfolio includes microcontrollers, power semiconductors and sensors. Photolithography is used in the manufacture of semiconductors, integrated circuit components, and printed circuit boards. Hot electrons arise generically at low temperatures even in degenerate semiconductors or metals. It is an electrically neutral quasiparticle that exists in insulators, semiconductors and some liquids. Amongst the family of conducting polymers and organic semiconductors, polyaniline has many attractive processing properties. These photon-emitting semiconductors are the so-called "direct bandgap" semiconductors.