Minority carrier lifetime degradation in carbon-doped base of InGaP/GaAs heterojunction bipolar transistors grown by low-pressure metalorganic 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 the minority carrier lifetime in the samples doped at 5.5 x 10(19) cm(-3) decreases upon annealing at only 600 degrees C. Magneto transport measurements were performed to obtain the minority carrier mobili ty, with which the minority carrier lifetime was extracted. The decrease in the direct current (dc) current gain upon annealing is attributed to the i ncrease in the base bulk recombination. The correlation between the dc curr ent gain and the magnetotransport measurements indicates that the annealing increases the carbon-related defects in the GaAs base, decreases the minor ity carrier lifetime in the carbon-doped base, and degrades the dc current gain of the InGaP/GaAs HBTs. These results are very important to the growth and postgrowth processing of InGaP/GaAs HBTs. (C) 2000 American Institute of Physics. [S0003-6951(00)04628-3].