PCAOB inspections repeatedly indicate deficiencies in audits of fair-value (FV) estimates, prompting regulators to improve the related auditing standards. We predict that auditor task-specific FV expertise, gained from work experience during the audit of FV measurements, can contribute to higher audit quality. Utilizing FV-related restatements and comment letters, we find that expertise in auditing Level 3 FV estimates at the office level is associated with greater FV audit quality. Level 2 FV expertise or national level FV expertise is not associated with higher FV audit quality. Following the receipt of a comment letter, we further find that auditor FV expertise is associated with lower comment letter remediation costs and higher FV disclosure quality. Finally, we find that the value relevance of Level 3 FV disclosures increases with the extent of auditor FV expertise. Collectively, our results highlight that auditor fair value expertise contributes to the credibility and usefulness of FV disclosures.
Amorphous oxide semiconductor-based thin film transistors (TFTs) have been considered as excellent switching elements for driving active-matrix organic light-emitting diodes (AMOLED) owing to their high mobility and process compatibility. However, oxide semiconductors have inherent defects, causing fast transient charge trapping and device instability. For the next-generation displays such as flexible, wearable, or transparent displays, an active semiconductor layer with ultrahigh mobility and high reliability at low deposition temperature is required. Therefore, we introduced high density plasma microwave-assisted (MWA) sputtering method as a promising deposition tool for the formation of high density and high-performance oxide semiconductor films. In this paper, we present the effect of the MWA sputtering method on the defects and fast charge trapping in In-Sn-Zn-O (ITZO) TFTs using various AC device characterization methodologies including fast I-V, pulsed I-V, transient current, low frequency noise, and discharge current analysis. Using these methods, we were able to analyze the charge trapping mechanism and intrinsic electrical characteristics, and extract the subgap density of the states of oxide TFTs quantitatively. In comparison to conventional sputtered ITZO, high density plasma MWA-sputtered ITZO exhibits outstanding electrical performance, negligible charge trapping characteristics and low subgap density of states. High-density plasma MWA sputtering method has high deposition rate even at low working pressure and control the ion bombardment energy, resulting in forming low defect generation in ITZO and presenting high performance ITZO TFT. We expect the proposed high density plasma sputtering method to be applicable to a wide range of oxide semiconductor device applications.
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