Metal organic vapor phase epitaxial growth of heavily carbon-doped GaAs using a dopant source of CCl3Br and quantitative analysis of the compensation mechanism in the epilayers

Abstract

Heavy carbon doping of GaAs by metal organic vapor phase epitaxy has been carried out using a dopant source of carbon trichloro bromide (CCl3Br), an intersubstituted compound of the two highly efficient dopant sources of CCl4 and CBr4. Results are being reported in the doping range of 1.76×1019–1.12×1020 cm−3, achieved at growth temperatures between 570 and 600 °C and V/III ratios between 10 and 50. The compensation mechanism of the carriers in the samples and its effect on the electrical and optical properties were systematically studied using double crystal x-ray diffraction, mobility, and photoluminescence measurements. A data analysis technique has been presented to quantitatively calculate the level of compensation in the layers from conventional lattice mismatch measurements. The antisite incorporation of carbon was found to be the dominant compensation mechanism for hole concentrations above 7.36×1019 cm−3. Room temperature mobility data of the samples showed a sharp deviation from the usual Hilsum’s fitting after the carrier concentration of 7.36×1019 cm−3, due to increased self-compensation of the epilayers. The optical properties of the samples were correlated to the self-compensation effect by the photoluminescence measurements carried out in the temperature range of 10–140 K.