Comparative analysis of dark current between SiN_xand polyimide surface passivation of an avalanche photodiode based on GaAs

Abstract

In this paper, we present the effects of different surface passivation types, one with SiN x and the other with polyimide (PI), on the dark (leakage) current of a GaAs-based avalanche photodiode. We identified that the reverse dark current originates from the surface, and not from the bulk, showing the nearly linear dependence on perimeters of active-mesa (A-M) up to 90% of breakdown voltage (V br ). From the theoretical results, total dark current consists of generation-recombination (G-R), shunt and tunneling components from a surface and the avalanche gain component from a bulk for both passivation types. Although the bulk component of avalanche gain•bulk current generates the breakdown process, it appears only near V br (12.7 V) because of a very small bulk current of a few fA in theory. For a surface current, SiN x passivation has values two to eight times lower than PI passivation. The different behaviors of surface current between passivation types could be theoretically explained by quantitative description of the current components.

Investigation of N2 plasma GaAs surface passivation efficiency against air exposure: Towards an enhanced diode

“…For metaloxide-semiconductor applications, interfacial passivation layers such as lanthanide oxynitride layers (LaON, NdON, CeON and GdON) [9] were used between the GaAs substrate and the dielectric gate. Si x N y layer was widely employed to passivate the sidewalls of LEDs [10], HBTs and photodiode devices [11][12][13]. Inorganic sulfide treatments (based on (NH 4 ) 2 S and Na 2 S) developed by Yablonovitch et al [14] have been used for several decades to passivate GaAs surface through the formation of Ga-S bonds [15].…”