ELECTRON-MOBILITY AND PHYSICAL MAGNETORESISTANCE IN N-TYPE GASB LAYERS GROWN BY MOLECULAR-BEAM EPITAXY

Electron mobility and low-field transverse physical magnetoresistance were measured in Te-doped GaSb layers grown by molecular beam epitaxy. The samples investigated had electron densities ranging from 10(16) t o 10(18) cm(-3); measurements were taken in the 8-300 K temperature ra nge. The high mobility values demonstrate that SnTe can be used as a s ource of Te doping with results comparable with GaTe. A detailed analy sis of the magnetoresistance data demonstrates that in samples with hi gh electron density (n approximate to 10(18) cm(-3)) the magnetoresist ance is mainly due to mixed conduction of electrons in both Gamma and L conduction band minima: the analysis gives the temperature dependenc e of the mu(Gamma) and mu(L) mobilities and of the E(L) - E(Gamma) ene rgy separation between L and Gamma edges. E(L) - E(Gamma) is 82 meV at 300 K and 67 meV at 8 K and exhibits a non-monotonic behaviour within the temperature range explored. In samples with low electron density (n approximate to 10(16) cm(-3)) the magnetoresistance is mainly due t o the energy distribution of carriers in the Gamma valley.