CHAPTER I

                             I NTRODUCT ION


     The goal of this study has been to measure and compare with theory the resistivity and Hall mobility of holes in silicon doped with gal lium and indium as functions of temperature and dopant density. Data taken on boron-doped silicon were also included in order to further confirm the adequacy of the theoretical model. In order to determine theoretically the resistivity and Hall mobility, one must first calculate the conductivity mobility, the density of holes, and the Hall factor. This can only be done with a thorough understanding of the energy band structure, the scattering mechanisms involved, and the carrier statistics.

     The application of an electric or a magnetic field to a crystal results in a variety of carrier transport phenomena. These phenomena are associated with the motion of current carriers in the conduction or valence bands. The free charge carriers in a semiconductor will acquire a drift velocity under the influence of an applied electric field. This velocity is the net result of the momentum gained from the externally a pplied field, and the momentum lost in collisions which tend to randomize the carrier momentum [1]. If the field is expressed in volts per centimeter, and the velocity in centimeters per second, a mobility is defined as the incremental average speed per unit electric field, and is expressed in squared centimeters per volt second. The velocity, and consequently the mobility, is dete rmined'by the different types of collisions which the carriers undergo.  Coll isions of-carriers with lattice atoms which