| Summary: | 碩士 === 國立嘉義大學 === 電子物理學系光電暨固態電子研究所 === 104 === In this experiment, the ZnO and MgZnO layers were deposited on sapphire substrate to form two-dimensional electron gas (2DEG) structure. Also the metal-semiconductor (M-S) and metal-oxide-semiconductor (MOS) field-effect transistor (FET) were fabricated. For 2DEG structure, the bottom ZnO layer is 300 nm and the top MgZnO layer with various thicknedd from 40 to 120 nm. Hall measurement shows that the thickest MgZnO layer (120 nm) demonstrates the highest carrier concentration (-2.27×〖10〗^19 〖cm〗^(-3)) and mobility (17.52〖cm〗^2/V-s).
The MOSFET with thin MgO layer is not easy to be saturated, however the MOSFET with thick MgO layer is easy to be saturated. The maximum transconductance gm occurs at VG=0V and decreases with increasing in VG. The gm of M-S FET is 1.23×〖10〗^(-3)ms/mm and the MOSFET with 5-min and 10-min are 1.16×〖10〗^(-4)ms/mm and 9.02×〖10〗^(-5)ms/mm, respectively. The threshold voltage VT of M-S FET is as high as -72 V and the VT is reduced to -11 V for the MOSFET with 10-min MgO layer. The M-S FET has maximum mobility of 1.27〖cm〗^2/V-s and the mobility is reduced in MOSFET.
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