Temperature dependence of galvanomagnetic properties for Gd doped and undoped p-type GaSe

The magnetoresistance and Hall effect measurements were carried out in undoped p-GaSe and Gd doped p-GaSe (p-GaSe:Gd) samples in the temperature range 90-320 K and 60-320 K, respectively. The transverse and longitudinal magnetoresistance coefficients for p-GaSe and p-GaSe:Gd samples decrease with increasing temperatures and were found to be M-J perpendicular to B and M-J parallel to B proportional to T-2.37 (90 less than or equal to T less than or equal to 320 K) for p-GaSe and M-J perpendicular to B and M-J parallel to B proportional to T-2.09 (60 less than or equal to T less than or equal to 320 K) for p-GaSe:Gd. The carrier concentration obtained from the Hall effect measurements in the p-GaSe:Gd sample increases up to 100 K, decreases in the range 100-140 K, increases in the range 140-280 K, and decreases in the range 280-320 K, although the carrier concentration in the p-GaSe sample continuously increases up to 320 K. Impurity energy levels calculated from ln(p/T-3/2) vs 10(3)/T for p-GaSe in the range 100-140, 140-220, and 220-320 K are E-c - 216 meV, E-v + 322 meV, and E-v + 573 meV, respectively, and for p-GaSe:Gd in the range 100-140, 140-260, and 280-320 K are E-c - 224meV, E-v + 330 meV, and E-c - 592 meV, respectively. In the same samples, the temperature dependence of the Hall mobilities of the p-GaSe and p-GaSe:Gd were found to be mu(H) proportional to T-2.09 (180 < T < 320) and mu(H) proportional to T-1.68 (180 < T < 320), respectively. The Hall mobilities for p-GaSe and p-GaSe:Gd are independent from the magnetic field at all sample temperatures. The electrical conductivities for both samples increase with increasing temperature and the electrical conductivity for p-GaSe is greater than that of p-GaSe:Gd for T > 120 K. (C) 1998 American Institute of Physics.