應用於低電壓無線通訊之假晶砷化鋁鎵/砷化銦鎵功率高電子遷移率電晶體之研究

Abstract

本論文實驗研究目的是在縮小元件佈局尺寸及汲極及源極間的距離，並將元件製作在以具有雙d攙雜通道的假晶砷化鋁鎵/砷化銦鎵的基材上，以期能達到高效益及高輸出功率之特性，以符合下一代微波無線通訊在低電壓操作之功率模組需求。 由於實驗過程中克服了在縮小元件尺寸後製程上的難度，使得元件之尺寸達到本實驗室實驗所能製作尺寸之最小尺寸，同時使用雙d攙雜通道假晶HEMT，因此此HEMT元件的在直流及特性均有優異表現。閘極寬3.36mm的元件具有265 mA/mm的最大電流密度以及11 V的閘極-汲極崩潰電壓(gate-to-drain breakdown voltage)，最大互導率超過336 mS/mm，和-1.1 V的夾止電壓 ( pinch-off voltage)。此3.36mm的元件，在2.4 V操作電壓及1.9 GHz頻率下亦符合PHS系統規格要求，在Pout = 22 dBm時，其600KHz之ACP有-57.58dBc。而閘極寬6.72 mm的元件在1.2 V操作電壓及1.9 GHz頻率下亦符合PHS系統手機規格要求，在Pout = 22 dBm時，其600KHz之ACP有-55.91 dBc 。而閘極寬20.16 mm的元件在1.9 GHz，2.4 V和 3.4 V 偏壓量測下，其在P1dB的功率效益分別為47.52 %及45.61 %，其最大輸出功率分別為30.06 dBm和32.37 dBm，並且均有良好的線性度。 因此在本實驗中驗證了在縮小元件佈局尺寸，元件特性均有優異表現。並且20.16 mm的元件在低電壓操作下能達到輸出功率1W，及61.54 %高效益。以期未來能在低電壓電池操作的無線通訊之功率有極大發長潛力。

A high efficiency and high output power for low voltage operation dual delta doped AlGaAs/InGaAs/GaAs Pseudomorphic High Electron Mobility Transistor ( PHEMT ) has been developed in this research. The device is ideal for the hand-held phone applications for next generation wireless communication. The device was designed and processed with reduced device layout of drain-to-source spacing. The DC and RF characteristics of the P-HEMT were measured. The 3.36-mm-wide device exhibited a saturation current density of 265 mA/mm with a gate drain breakdown voltage of 11 V. The maximum transcondutance Gm of the device was 336 mS/mm.and the pinch-off voltage was -1.1 V. The 20.16-mm-wide device operating at a drain bias of 2.4 volt at 1.9 GHz gives a Pout of 30dBm with an efficiency of 61 %. The high linearity and high power efficiency and high efficiency of the device at 2.4 volt bias is attributed to the dual delta doped PHEMT structure and the reduction of the size of the device layout. The dual delta doped structure has high drain current density, high electron mobility and low knee voltage and the reduction in the size of the device layout results in low source resistance and low turn-on resistance for the device.