Surface passivation of In0.83Ga0.17As photodiode with high-quality SiN layer fabricated by ICPCVD at the lower temperature

The surface passivation of low-temperature-deposited SiN_x films has been investigated in PIN type In_0.83Ga_0.17As photodiodes. In contrast to SiN_x films (330 °C) fabricated by PECVD (Plasma enhanced chemical vapor deposition), the low-temperature-deposited SiN_x films (75 °C) fabricated by ICPCVD (Inductively coupled plasma chemical vapor depositon) have a good effect on passivation of In_0.83Ga_0.17As photodiodes, which caused reductions of dark current as large as 2–3 orders of magnitude at the same test temperature 200 K. The effects of low-temperature-deposited SiN_x passivations with lowrate (∼16 nm/min) model were compared to the ones with highrate (∼100 nm/min) model. SiN_x films with lowrate model have a better effect on reducing dark current of the photodiodes. The different SiN_x films were studied by SIMS. The results show that the content of oxides in SiN_x layer fabricated by PECVD is 2 orders of magnitude more than that in SiN_x layer fabricated by ICPCVD which could be the reason that low-temperature-deposited SiN_x passivation leads to higher performance. Further, the dark current density of the photodiodes with lowrate-deposited SiN_x passivations does not show the dependence on the perimeter-to-area(P/A) of the junction.     

Interface property of silicon nitride films grown by inductively coupled plasma chemical vapor deposition and plasma enhanced chemical vapor deposition on In0.82Al0.18As

Au/silicon nitride/In_0.82Al_0.18As metal insulating semiconductor (MIS) capacitors were fabricated and then investigated by capacitance voltage (C–V) test at variable frequencies and temperatures. Two different technologies silicon nitride (SiN_x) films deposited by inductively coupled plasma chemical vapor deposition (“ICPCVD”) and plasma enhanced chemical vapor deposition (“PECVD”) were applied to the MIS capacitors. Fixed charges (N_f), fast (D_it) and slow (N_si) interface states were calculated and analyzed for the different films deposition MIS capacitors. The D_it was calculated to be 4.16 × 10¹³ cm⁻² eV⁻¹ for “ICPCVD” SiN_x MIS capacitors, which was almost the same to that of “PECVD” SiN_x MIS capacitors. The D_it value is obviously higher for the extended wavelength In_xGa_1−xAs (x > 0.53) epitaxial material as a result of lattice mismatch with substrate. Compared to the results of “PECVD” SiN_x MIS capacitors, the N_si was significantly lower and the N_f was slightly lower for “ICPCVD” SiN_x MIS capacitors. X-ray photoelectron spectroscopy (XPS) analysis shows good quality of the “ICPCVD” grown SiN_x. The low temperature deposited SiN_x films grown by “ICPCVD” show better effect on decreasing the dark current of In_xGa_1−xAs photodiodes.