The transport properties in a magnetic field of the p-type space charge region adjacent to 20° tilt grain boundaries in n-type germanium bicrystals were investigated as a function of a reverse bias voltage between bulk and grain boundary (field effect). The average HALL mobility at 77°K of the holes decreased with increasing bias, demonstrating the existence of a size effect caused by diffuse boundary scattering in connection with the small width of the space charge layer. The results obtained for symmetrical bias are in agreement with a simplified theory based on a constant space charge field and allow to estimate an average hole density. The transverse magnetoresistance also decreased with increasing field effect-voltage, as expected.
Kombination von galvanomagnetischen- und Feldeffekt-Messungen an Germanium-Bikristallen