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However, mobility is much more commonly expressed in cm 2 /(V⋅s) = 10 −4 m 2 /(V⋅s). Mobility is usually a strong function of material impurities and temperature, and is determined empirically. Mobility values are typically presented in table or chart form. Mobility is also different for electrons and holes in a given material.
In a semiconductor with a single carrier type, the magnetoresistance is proportional to (1 + (μB) 2), where μ is the semiconductor mobility (units m 2 ·V −1 ·s −1, equivalently m 2 ·Wb −1, or T −1) and B is the magnetic field (units teslas).
In semiconductor lasers, the carrier lifetime is the time it takes an electron before recombining via non-radiative processes in the laser cavity. In the frame of the rate equations model , carrier lifetime is used in the charge conservation equation as the time constant of the exponential decay of carriers.
1.6 × 10 −27 These carrier concentrations will change if these materials are doped. For example, doping pure silicon with a small amount of phosphorus will increase the carrier density of electrons, n .
The invention of the high-electron-mobility transistor (HEMT) is usually attributed to physicist Takashi Mimura (三村 高志), while working at Fujitsu in Japan. [4] The basis for the HEMT was the GaAs (gallium arsenide) MOSFET (metal–oxide–semiconductor field-effect transistor), which Mimura had been researching as an alternative to the standard silicon (Si) MOSFET since 1977.
The drift velocity, and resulting current, is characterized by the mobility; for details, see electron mobility (for solids) or electrical mobility (for a more general discussion). See drift–diffusion equation for the way that the drift current, diffusion current, and carrier generation and recombination are combined into a single equation.
The proportionality constant is known as mobility of the carrier, which is a material property. A good conductor would have a high mobility value for its charge carrier, which means higher velocity, and consequently higher current values for a given electric field strength. There is a limit though to this process and at some high field value, a ...
The term "hot electron" comes from the effective temperature term used when modelling carrier density (i.e., with a Fermi-Dirac function) and does not refer to the bulk temperature of the semiconductor (which can be physically cold, although the warmer it is, the higher the population of hot electrons it will contain all else being equal).