Conductance properties of as-grown and annealed MBE GaAs layers grown at temperatures between 200 and 420/spl deg/C

Precise temperature dependent conductivity measurements are carried out and the room temperature band and hopping components of the conductivity are determined for as-grown and annealed (590/spl deg/C, 10 min) MBE GaAs layers grown at various temperatures between 200 and 420/spl deg/C. It is found that the hopping conductivity strongly decreases and the band conductivity slightly changes with increasing growth temperature. The /spl sigma//sub hop/ to /spl sigma//sub band/ ratio decreases from 1/spl times/10/sup 6/ to 2/spl times/10/sup -2/ in as-grown layers and from 2/spl times/10/sup 2/ to 2/spl times/10/sup -3/ in annealed layers with increased growth temperature from 200 to 420/spl deg/C. The band and hopping components are comparable for unannealed layer grown at 400/spl deg/C and annealed layer grown at 350/spl deg/C. Layers grown at <350/spl deg/C are lattice mismatched in as-grown state. Further it is found that layers with dominating hopping show different electrical breakdown properties than layers with dominating band conductance.