The effect of substrate temperature on the isolation of n-type GaAs layersusing MeV boron implantation

The evolution of sheet resistivity (R-s) with annealing temperature in n-ty pe GaAs layers irradiated with B-11(+) at different target temperatures has been investigated. The n-type material was prepared using multi-energy imp lants of Si-29(+) ions. An isolation region was formed using boron ions at single energy of 1.5 MeV with doses of 2 x 10(14) cm(-2) into samples held at RT, 100 and 200 degreesC. Sample resistivity was measured at room temper ature both before and after annealing in the temperature range 350-800 degr eesC. Maximum resistivity values were achieved after annealing at 500 degre esC for all three sets of samples. Annealing at higher temperatures returne d the resistivity to a value close to that of the starting material and thi s recovery of conductivity was fastest in case of RT implants. Formation of thermally stable defects at high target temperatures was thought to be res ponsible for the different evolution trend of sheet resistivity with anneal ing temperature in samples irradiated at 100 and 200 degreesC compared to t hose irradiated at RT.