Electronic properties in Ga-doped CdTe layers grown by metalorganic vapor phase epitaxy

Electronic properties in Ga-doped (100) CdTe layers on (100) GaAs grown by atmospheric pressure metalorganic vapor phase epitaxy were studied. Triethylgallium was used as a dopant source. The source materials were dimethylcadmium (DMCd) and diethyltelluride (DETe). The effects of the DETe/DMCd (VI/II) ratio on the electrical properties were evaluated by Hall measurements. Electron concentration (300 K) was controlled from 3.5×10¹⁴ cm^-3 to 2.5×10¹⁶ cm^-3 by the VI/II ratio in the range 0.5 to 2. Higher growth temperature lowered the electron concentration. High electron mobility of 630 cm²/V s (300 K) was obtained for a growth temperature of 375 °C and a VI/II ratio of 2. Good correspondence was observed between electrical and photoluminescence (PL) properties. Both intensity and linewidth of a neutral-donor bound-exciton (D⁰,X) emission at 1.5932 eV increased with the electron concentration. The ionization energy of the Ga donor was estimated to be about 18 meV from electrical and PL properties. A Ga incorporation mechanism was deduced on the basis of the experimental results.