Complex conductivity characterization of InGaZnO films using terahertz time-domain spectroscopy

초록

Oxide semiconductors have attracted significant attention as strong candidate materials for ultrahigh-resolution displays and stackable memory applications. However, owing to the increasing complexity of advanced process technologies, tracking changes in the electrical properties of oxide semiconductors caused by subsequent upper-layer processes is becoming increasingly challenging. Consequently, non-destructive optical methods for evaluating the electrical properties of oxide semiconductors are gaining importance. To optically verify the intrinsic electrical properties, this study proposes terahertz time-domain spectroscopy (THz-TDS) as an effective tool for measuring the complex conductivities of InGaZnO (IGZO) films. Electrical and complex conductivities are compared for 500–700 nm thick IGZO films prepared under 0 %–10 % oxygen partial pressures (PO2). The results demonstrate that with increasing IGZO film thickness and decreasing PO2, both the electrical and complex conductivities tend to increase. Furthermore, changes in the electrical and optical conductivities are investigated for an IGZO film with an O 1s peak using X-ray photoelectron spectroscopy analysis. This study demonstrates that THz-TDS can optically measure the intrinsic properties of semiconductor materials, highlighting its significant potential for both academic and industrial applications.

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