HALL-EFFECT MEASUREMENTS ON CR FILMS DEPOSITED ON GE SUBSTRATES

The Hall effect of Cr films on Ge substrates was measured at room temp erature in a high-vacuum system. It was found that the Hall coefficien t R(H) depends on the pressure in the vacuum system. R(H) of films abo ut 1-2 nm thick was about 5x10(-11) m(3)/C for a pressure during Cr ev aporation in the 10(-7) Torr range. The Hall coefficient decreased to less than 10(-11) m(3)/C if pressure decreased into the 10(-8) Torr ra nge. These R(H) values are much lower than found in bulk chromium. The y would give in a one-band model about 1 electron hole/atom for the hi gher-pressure, and about 12 electron holes/atom for the lower-pressure experiments. A two-band model could give the observed low Hall coeffi cients if the hole current nearly compensated the electron current. Bo th models cannot be reconciled with presently accepted electron band m odels for chromium. (C) 1996 American Institute of Physics.