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

Abstract

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 ( $Q$ $_{\text{eff}}$ ) and interface defect density ( $D$ $_{\text{it}}$ ) varied from $-$ 3.0 $\times$ 10 $^{10}$ to 2.5 $\times$ 10 $^{11}$ cm $^{-2}$ and 2.5 $\times$ 10 $^{10}$ to 5.7 $\times$ 10 $^{11}$ eV $^{-1}$ $\cdot$ 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 $\mu$ s from the initial value of 2 $\mu$ s.