<Dl> <Dd> v d = μ E (\ displaystyle \, v_ (d) = \ mu E). </Dd> </Dl> <Dd> v d = μ E (\ displaystyle \, v_ (d) = \ mu E). </Dd> <P> Electron mobility is almost always specified in units of cm / (V s). This is different from the SI unit of mobility, m / (V s). They are related by 1m / (V s) = 10 cm / (V s). </P> <P> Conductivity is proportional to the product of mobility and carrier concentration . For example, the same conductivity could come from a small number of electrons with high mobility for each, or a large number of electrons with a small mobility for each . For metals, it would not typically matter which of these is the case, since most metal electrical behavior depends on conductivity alone . Therefore mobility is relatively unimportant in metal physics . On the other hand, for semiconductors, the behavior of transistors and other devices can be very different depending on whether there are many electrons with low mobility or few electrons with high mobility . Therefore mobility is a very important parameter for semiconductor materials . Almost always, higher mobility leads to better device performance, with other things equal . </P>

Mobility of the electrons in a material is expressed in units of