(Invited) Extraction of Trap Densities in TFTs using C-V Characteristics

Abstract

We will introduce device characterizations based on low-frequency capacitance-voltage methods and numerical analysis. First, surface potential is acquired, next, spatial distribution of the trap states is assumed, and finally, trap densities are extracted. We will also show results acquired for various kinds of TFTs as examples of the device characterizations.

An Empirical Modeling of Gate Voltage-Dependent Behaviors of Amorphous Oxide Semiconductor Thin-Film Transistors including Consideration of Contact Resistance and Disorder Effects at Room Temperature

“…As for a physical interpretation, the conduction band of the AOS, e.g., IGZO, is composed of spherical orbitals (i.e., s orbitals) of metal cations; thus, the AOS is insensitive to the bonding angle disorder, whereas amorphous Silicon has strong bonding directivity due to the sp3 orbitals of its conduction band [18][19][20]. However, the AOS still has a bonding distance error in the amorphous phase, alluding to the existence of localized traps associated with band tail states, which can be estimated using extraction methods based on the current-voltage and capacitance-voltage characteristics [18,21]. In order to minimize these localized traps, process conditions can be optimized in terms of the AOS target compositions for the sputtering process, oxygen partial pressure, and annealing temperature [1,3,22].…”

Study of Back-Channel Defect States on Bottom-Gate IGZO TFTs Using Capacitance-Voltage Analysis

“…Measuring C-V characteristics on a TFT is possible, however the effective capacitance of a TFT is extremely small (~1 pF), and measurement noise makes the interpretation of defect states exceedingly difficult. While researchers have addressed this by using sophisticated measurement systems [2], the approach in this work is to perform C-V analysis on interdigitated capacitors (IDC) designed to provide a much larger area while still representing the TFT channel region. Both C-V and I-V datasets were used to develop a comprehensive IGZO material/device model.…”