A Simple Method to Fabricate a Sub-micron Gate for GaAs Power MESFET's
利用此簡易方法製造出的MESFET元件在汲極電壓為2.5伏特時，其最大互導率（transconductance）高達180 mS/mm，此元件亦通過個人手攜式電話（PHS）之π/4-DQPSK標準，當輸出功率為19 dBm時，距1.9 GHz中心頻率600 kHz的鄰近頻道功率（ACP）為54 dBc，此元件在2.2伏特操作電壓時具有22.7 dBm的輸出功率及66.4%的功率效率，其鄰近頻道功率為50.6 dBc。
In this thesis, a simple fabrication process of sub-micron gate was applied to MESFET. The sub-micron gate was fabricated using the PECVD and the RIE. Detail processing techniques were described in this thesis. The proper process control ensured good device performance. The sub-micron gate is used to imoprove the transconductance and power efficiency of the GaAs MESFET. The most important indicator, transconductance, of device quality for microwave applications is as high as 180 mS/mm. The power characteristics of the GaSAs MESFET were measured by a power tuning system, in which the π/4-DQPSK modulated PHS. The device was operated at a drain bias of 2.2 V and under the class AB condition with a quiescent drain current of 80 mA. The PAE became 66.4% and the Padj was 50.6 dBc when the Pout was increased to 22.7 dBm. In the results, the sub-micron gate MESFET fabricated using the simple gate process has shown good potential for the advanced wireless communication applications.
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