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There are two recognized types of charge carriers in semiconductors.One is electrons, which carry a negative electric charge.In addition, it is convenient to treat the traveling vacancies in the valence band electron population as a second type of charge carrier, which carry a positive charge equal in magnitude to that of an electron.
There are two causes of charge carrier motion and separation in a solar cell: drift of carriers, driven by the electric field, with electrons being pushed one way and holes the other way; diffusion of carriers from zones of higher carrier concentration to zones of lower carrier concentration (following a gradient of chemical potential).
As an application example, the steady-state space-charge-limited current across a piece of intrinsic silicon with a charge-carrier mobility of 1500 cm 2 /V-s, a relative dielectric constant of 11.9, an area of 10 −8 cm 2 and a thickness of 10 −4 cm can be calculated by an online calculator to be 126.4 μA at 3 V. Note that in order for this ...
In solid-state physics of semiconductors, carrier generation and carrier recombination are processes by which mobile charge carriers (electrons and electron holes) are created and eliminated. Carrier generation and recombination processes are fundamental to the operation of many optoelectronic semiconductor devices , such as photodiodes , light ...
To provide a definition of current independent of the type of charge carriers, conventional current is defined as moving in the same direction as the positive charge flow. So, in metals where the charge carriers (electrons) are negative, conventional current is in the opposite direction to the overall electron movement.
The two different mechanisms result in different charge mobilities. In disordered solids, disordered potentials result in weak localization effects (traps), which reduce the mean free path, and hence the mobility, of mobile charges. Carrier recombination also decreases mobility.
Charge carrier density, also known as carrier concentration, denotes the number of charge carriers per volume. In SI units, it is measured in m −3. As with any density, in principle it can depend on position. However, usually carrier concentration is given as a single number, and represents the average carrier density over the whole material.
Franklin thought of the charge carrier as being positive, but he did not correctly identify which situation was a surplus of the charge carrier, and which situation was a deficit. [ 23 ] Between 1838 and 1851, British natural philosopher Richard Laming developed the idea that an atom is composed of a core of matter surrounded by subatomic ...