Measurement of Hall coefficient of a semiconductor

Manual

1. FG. CARRIER SEPARATION DUE TO A MAGNETIC FIELO

3. cr

Where j and jay are the mobilities of holes and electrons; p and n are the carrier
densities of holes and electrons. Eq. (5) correctly reduces to equation (3) when only

Since the mobilities jy and py are not constants but function of temperature CT) the
att co ven by Eq, (5), is also a function of T and it may become zero, even
Ichange sign. In general j > li so that inversion may happen only if p >; thus "Hall
coefficient inversion is characteristic only of p-type semiconductors,

Au the point of zero Hall cocfficiet, it is possible to determine the ratio of mobilities
nd ther relative concentration

Thus we see that the Hall coefficient, in conjunetion with resistivity measurement,

an provide information on carrer densities, mobilities, impurity concentration and other

values, I must be noted, however, that mobilities obtained from Hall Effect measurements
= Re do not always agree with directly measured values. The reason being that carters
ate distributed in energy, and those with higher velocities will be d to a greater

extent fora given field, As we know varis with carrier velocity