| Summary: | 碩士 === 逢甲大學 === 電子工程所 === 97 === This work reports, a transparent Aluminum-doped zinc oxide (AZO) gate material deposited on AlGaAs/InGaAs δ-doped pseudomorphic high electron mobility transistors have been prepared by RF reactive magnetron sputtering system from an AZO target was prepared by mixing 99.99% ZnO and Al2O3 powders with the weight percentage ratio of 98:2. The distance between target and substrate is 3 cm and deposition power, deposition pressure and deposition rate are 15 W, 1 mtorr, and 1.5 nm/min. The substrate temperature is 200°C. Therefore, the DC characteristics, RF characteristics, and temperature-dependent characteristics of the AZO-HEMT have been compared with the conventional Au-gate pHEMT, and the measurement of the optical characteristics of the transparent AZO-HEMT.
In comparison, the proposed devices employing with transparent AZO gate (AZO-HEMT), and convention Au gate device (Au-HEMT) have been investigated. AZO-HEMT (Au-HEMT) have demonstrated superior two-terminal gate-drain breakdown and turn-on voltages of -63 (-13.4) and 3.4 (1.2), the maximum extrinsic transconductance (gm,max) of 137 (140) mS/mm, the drain-source saturation current density (IDSS) of 220.4 (210.5) mA/mm, the gate-voltage swing (GVS) of 1.18 (1.01) V, and the intrinsic voltage gain of 257 (214) at VDS = 3 V, at room temperature, with gate dimensions 1.2 × 100 μm2.
From experimental results, the AZO-HEMT exhibited the better two-terminal breakdown performance, intrinsic voltage gain and temperature-dependent characteristics. Besides, the AZO-HEMT shows the lower output conductance, the higher intrinsic voltage gain and the higher two-terminal breakdown voltage, therefore, the AZO-HEMT shows high transmittance of 88 % ~ 98 % within the wavelength of 400 nm ~ 900 nm of the AZO gate can enable the implementation of direct optical characterization and optoelectronic integrated circuit (OEIC) applications.
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