We have studied deep levels in AlGaInP emitter of AlCaInP/GaAs heterojuncti
on bipolar transistor by deep-level transient spectroscopy and photolumines
cence (PL) methods. Two deep levels were obtained with thermal activation e
nergies of E-c - E-t1 = 0.42 eV and E-c - E-t2 = 0.59 eV, whose capture cro
ss sections are 6.27 x 10(-17) cm(2) and 6.49 x 10(-20) cm(2), where E-t1 a
nd E-t2 are Si-related and O-related deep levels, respectively. The relatio
nship between excitation power and PL peak intensity have revealed that non
radiative recombination centers of deep levels exist in AlGaInP. The curren
t gain of AlGaInP/GaAs HBT decreases due to the existence of deep levels in
AlGaInP.