In Situ Growth of Al2O3 as a Passivation and Antireflection Layer on TiO2-Based MSM Photodetectors

The in situ growth of Al
₂
O
₃
on TiO
₂
by ultrasonic spray pyrolysis deposition is presented in this paper. Here, Al
₂
O
₃
is used as the passivation and the antireflection layer. TiO
₂
-based photodetectors (PDs) with Al
₂
O
₃
, SiO
₂
, and no passivation layers were studied. It was found that the PD without the passivation layer has the highest dark current and photocurrent due to high internal photoconductive gain related to the reaction between the oxygen molecule and TiO
₂
. The PDs with Al
₂
O
₃
and SiO
₂
passivation layers suppress the internal photoconductive gain and show stable I -V characteristics after the PDs are exposed to air for 30 days. The device with the Al
₂
O
₃
passivation layer showed the most stable I-V characteristics and the highest detectivity and the shortest response time among the three devices.