Extraction of Density of States in Amorphous GaInZnO Thin-Film Transistors by Combining an Optical Charge Pumping and Capacitance–Voltage Characteristics

摘要

A technique for extracting the acceptorlike density of states (DOS) of $n$ -channel amorphous GaInZnO (a-GIZO) thin-film transistors based on the combination of subbandgap optical charge pumping and $C$– $V$ characteristics is proposed. While the energy level is scanned by the photon energy and the gate voltage sweep, its density is extracted from the optical response of $C$–$V$ characteristics. The extracted DOS shows the superposition of the exponential tail states and the Gaussian deep states ($N_{rm TA} = hbox{2} times hbox{10}^{18} hbox{eV}^{-1} cdot hbox{cm}^{-3}$, $N_{rm DA} = hbox{4} times hbox{10}^{15} hbox{eV}^{-1} cdot hbox{cm}^{-3}$, $kT_{rm TA} = hbox{0.085} hbox{eV}$, $kT_{rm DA} = hbox{0.5} hbox{eV}$ , $E_{O} = hbox{1} hbox{eV}$). The TCAD simulation results incorporated by the extracted DOS show good agreements with the measured transfer and output characteristics of a-GIZO thin-film transistors with a single set of process-controlled parameters.