Compositionally graded C-doped In/sub 1-x/Ga/sub x/As base in InP/InGaAs D-HBTs grown by MOCVD with low base sheet resistance and high current gain

Abstract

MOCVD-grown carbon(C>doped InGaAs layers using CBr4 as a C source were investigated with the Van der Pauw method and PL measurement. A hole concentration of as high as 7 X IOI9 was obtained at a growth temperature of 385 "c. However, PL intensity of the C-InGaAs &pen& on the growth temperature, and was weaker than that of Mg-or Zn-doped InGaAs at a range of over I X IOi9Furthermore. IDC measurement of DHBTs revealed that there existed a strict t r a b f f between the current gain and base sheet resistance of C-InGaAs unifombase D-HBTs. To break through the tradeoff, we have fabricated D-HBTs with 150-nm-thick strain-compensated gra&d-In,-XGaxAs-base (X=0.4230.53). As a result, a current gain of 55 with a base shect resistance of 480 Q/o were achieved.