IMPROVEMENT IN DARK CURRENT CHARACTERISTICS AND LONG-TERM STABILITY OF MESA INGAAS/INP P-I-N PHOTODIODES WITH 2-STEP SINX SURFACE PASSIVATION

We report the sucessful fabrication of mesa In0.53Ga0.47As/InP p-i-n photodiodes passivated with SiN(x) films. The SiN(x) films were deposited by plasma-enhanced chemical vapor deposition in two steps. First, a thin SiN(x) film was deposited at low temperature (50-150-degrees-C) and then annealed at high temperature (250-350-degrees-C) for 30-60 min to hydrogenate and nitridize the mesa surfaces simultaneously. Second, a thick SiN(x) film was deposited at the annealing temperature to serve as a surface passivation and antireflective layer. Improvement in dark-current and long-term stability, compared to the results obtained from devices with one-step SiN(x) surface passivation previously reported, has been achieved. The life tests at -20 V and 180/300-degrees-C on these devices have shown a stable dark current for over 1500 h.