Electrical and Material Characterization of the Stability of ALGaAs and GaAs Planar Doped Structures

In this work we have studied the effects of silicon planar doping on the electrical and optical properties of GaAs, and the effects of rapid thermal annealing on AIGaAs planar-doped structures. MBE-grown GaAs epilayers with multiple planar-doped layers displayed a 1.2 eV photoluminescence peak, presumably due to gallium vacancy - donor complexes, for samples with nominal silicon sheet densities much greater than measured charge densities. The Hall mobilities of these samples were also reduced compared to both uniformly-doped and planar-doped structures whose silicon areal densities were more nearly equal to measured sheet charge densities, although X-Ray rocking curves were nearly identical in all cases. Planar-doped AIGaAs Schottky diodes had nearly ideal electrical characteristics. Rapid thermal annealing of the planar-doped structures before fabrication increased the diode ideality factor from n=1.06 to n=1.60, seriously degraded the saturation current and breakdown voltage, and increased the doping profile FWHM from 60Å to 170Å.