Precipitate formation in carbon-doped base of InGaP/GaAs heterojunction bipolar transistors grown by low-pressure metal organic chemical vapor deposition
The effect of intermediate temperature annealing on the carbon-doped base region of InGaP/GaAs heterojunction bipolar transistors (HBTs) was studied. This work shows that after annealing at only 600 °C a sample doped at 5.5×1019 cm−3 displays carbon precipitation. InGaP/GaAs HBT structures were grown for the annealing study. Hall measurements were used to measure hole concentration. Atomic force microscopy was employed to identify carbon precipitation. The annealing process not only removes hydrogen from the base but also creates carbon precipitates. The dc current gain measurements imply that the carbon precipitates increase base recombination. These results are very important in the growth and postgrowth annealing of high gain HBTs.
Abstract The first-principles calculations have been performed to study the structural, elastic, mechanical and electronic properties of cubic OsTM (TM = Ti, Zr, and Hf) and hexagonal TMOs 2 compounds. The calculated structural parameters are in good agreement with the available experimental data. To the best of our knowledge, the elastic constants of OsTM and TMOs 2 compounds have been obtained for the first time. The calculated elastic and mechanical properties show that these compounds have no superhard character. These compounds are mechanically stable and behave in ductile manner. The electronic band structures and densities of states of OsTM and TMOs 2 compounds have been analysed. OsTM has a mixture of covalent-ionic and metallic character, and TMOs 2 has strong metallic nature.