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 r egion of InGaP/GaAs heterojunction bipolar transistors (HBTs) was studied. This work shows that after annealing at only 600 degrees C a sample doped a t 5.5X10(19) cm(-3) displays carbon precipitation. InGaP/GaAs HBT structure s were grown for the annealing study. Hall measurements were used to measur e hole concentration. Atomic force microscopy was employed to identify carb on 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 resu lts are very important in the growth and postgrowth annealing of high gain HBTs. (C) 1999 American Institute of Physics. [S0003-6951(99)00620-8].