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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 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.
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 carrier density is important for semiconductors, where it is an important quantity for the process of chemical doping.Using band theory, the electron density, is number of electrons per unit volume in the conduction band.
Semiconductor characterization techniques are used to characterize a semiconductor material or device (p–n junction, Schottky diode, solar cell, etc.).Some examples of semiconductor properties that could be characterized include the depletion width, carrier concentration, carrier generation and recombination rates, carrier lifetimes, defect concentration, and trap states.
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 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.
This greater energy affects the mobility of charge carriers and as a consequence affects how they travel through a semiconductor device. [3] Hot electrons can tunnel out of the semiconductor material, instead of recombining with a hole or being conducted through the material to a collector. Consequent effects include increased leakage current ...