Reduced thermal conductivity in low-temperature-grown GaAs

Thermal conductivity of low-temperature-grown GaAs(LT GaAs) was measured at room temperature using a self-heated photolithographically patterned platinum wire on the surface of the sample. Finite element calculations were performed to extract the thermal conductivity from the nonlinear $\mathrm{I–V}$ characteristic of the wires. For LT GaAs grown at a substrate temperature of $\text{240\hspace{0.05em}°}\mathrm{C},$ the thermal conductivity was found to be only 23% of the value for stoichiometric GaAs. Rapid thermal annealing of the sample at $\text{650\hspace{0.05em}°}\mathrm{C}$ for 30 s increased the thermal conductivity to 46% of the GaAs value. Strong phonon scattering by point defects could account for reduced thermal conductivity in the as-grown material. The reduced thermal conductivity in the annealed material, however, is not consistent with our current understanding of the defects in annealed LT GaAs.