Differential Ideality Factor Technique for Extraction of Subgap Density of States in Amorphous InGaZnO Thin-Film Transistors
2012; Institute of Electrical and Electronics Engineers; Volume: 33; Issue: 3 Linguagem: Inglês
10.1109/led.2011.2182602
ISSN1558-0563
AutoresMinkyung Bae, Daeyoun Yun, Yongsik Kim, Dongsik Kong, Hyun Kwang Jeong, Woojoon Kim, Jaehyeong Kim, Inseok Hur, Dae Hwan Kim, Dong Myong Kim,
Tópico(s)Silicon and Solar Cell Technologies
ResumoWe propose a differential ideality factor technique (DIFT) for extraction of subgap density of states (DOS) over the bandgap in amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) by using the differential ideality factor $d\eta/dV_{\rm GS}$ on behalf of the ideality factor itself. Contrary to the subthreshold current method which requires an accurate threshold voltage $(V_{T})$ , the DIFT is free from $V_{T}$ itself and considerably useful to TFTs with a nonuniform distribution of DOS over the bandgap. Through the DIFT applied to an a-IGZO TFT with $W/L = \hbox{200}\ \mu \hbox{m}/\hbox{30}\ \mu\hbox{m}$ , the subgap DOS is extracted to be a superposition of exponential deep and tail states with $N_{\rm DA} = \hbox{7.1} \times \hbox{10}^{15}\ \hbox{cm}^{-3} \cdot \hbox{eV}^{-1}$ , $kT_{\rm DA} = \hbox{0.6}\ \hbox{eV}$ , $N_{\rm TA} = \hbox{1.5} \times \hbox{10}^{16}\ \hbox{cm}^{-3} \cdot \hbox{eV}^{-1}$ , and $kT_{\rm TA} = \hbox{0.024}\ \hbox{eV}$ .
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