In this thesis, the passivation of InP/InGaAs heterojunction bipolar phototransistor(HPT) for anti-reflection coating is investigated. Various Silicon Nitride $(SiN_x)$ deposition condition for anti-reflection coating is tried on Heterojunction Bipolar Phototransistor (HPT). The effect of anti-reflection coating of $SiN_x$ on HPT is confirmed by electrical, optical response and compared with other passivation condition (conventional $SiN_x$ deposition condition, proposed $SiN_x$ deposition condition, polyimide, BCB).
Measurement is performed to electrical, optical characteristics of HPT. In optical characteristics measurement, the light with a wavelength of 1.55 um is illuminated on the top-side of HPT. Among the various $SiN_x$ deposition condition, the case of $SiN_x$ deposition condition of temperature ramping shows more enhancement than conventional $SiN_x$ deposition condition. But HPTs with passivated by new $SiN_x$ deposition condition in this thesis do not reach the performance of conventional HPT that passivated by polyimide, BCB. So, to analysis this phenomenon, PL(Photoluminescence) experiment for indirect means of surface state evaluation is carried out for finding cause. Through PL experiment, the cause of HPT degradation by $SiN_x$ depostion is suspect to the stress effect of $SiN_x$ film.
