Effects of Process Parameters on the Passivation Properties of Anodic Aluminum Oxide/Silicon Interface

In this paper, surface passivation properties of anodic aluminum oxide (AAO) on silicon substrate has been investigated. Metal-insulator-semiconductor with AAO as a dielectric layer is fabricated, and AAO/Si interface charges are evaluated from the capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics. It has been observed that the effective charge density (Q
_eff
) and interface defect density (D
_it
) varied from -3.0 × 10
¹⁰
to 2.5 × 10
¹¹
cm
^-2
and 2.5 × 10
¹⁰
to 5.7 × 10
¹¹
eV
^-1
·cm
^-2
, respectively, depending on the process conditions such as molarity of the electrolyte, electrolyte temperature, applied dc-bias voltage, and the type of the electrolyte used for growth of AAO through the electrochemical anodization process. Further, capacitance transient (C-t) characteristics are used to evaluate the minority carrier lifetime, and it is found that the use of the AAO passivation layer increases minority carrier lifetime to 90 μs from the initial value of 2 μs.