Investigation of Mg X Zn 1− X O/ZnO Heterojunction Thin-Film Transistors Fabricated Using Mist-Chemical Vapor Deposition.

This study investigates heterojunction thin-film transistors (HTFTs) with Mg $_{X}$ Zn $_{1- {X}}\text{O}$ /zinc oxide (ZnO) heterojunctions deposited using mist chemical vapor deposition (mist-CVD). The X-ray diffraction patterns indicate that the mist-CVD deposited Mg $_{X}$ Zn $_{1- {X}}\text{O}$ /ZnO heterojunctions are ${c}$ -axis oriented. Different Mg/Zn ratios (0.1/0.9, 0.2/0.8, and 0.3/0.7) and Mg $_{X}$ Zn $_{1- {X}}\text{O}$ thickness (15, 30, 45 nm) are used to form the Mg $_{X}$ Zn $_{1- {X}}\text{O}$ /ZnO heterojunctions of HTFTs. The Mg0.3Zn0.7O (15 nm)/ZnO HTFT exhibits high field-effect mobility of 165.56 cm2V−1s−1 and steep subthreshold slope (SS) of 106 mV/dec, but low ON-/OFF-current ratio and high gate leakage current. The Mg0.3Zn0.7O (45 nm)/ZnO HTFT shows the largest ON-/OFF-current ratio of $8.4\times10$ 8 and low gate leakage current of 19.4 pA (at ${V}_{G} =5$ V)/0.27 pA (at ${V}_{G} = -5$ V) but sacrifices the field-effect mobility and SS. The Mg0.3Zn0.7O (30 nm)/ZnO HTFT with the optimum electrical characteristics is used to estimate the stability. It is found that the Mg0.3Zn0.7O/ZnO HTFT is more stable than the ZnO thin-film transistor (TFT). [ABSTRACT FROM AUTHOR]