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为了提高GaAs功率MESFET的输出线性度,器件有源层掺杂分布的改进是一种 有效的手段。本文探索了有源层掺杂分布与器件输出线性度之间的关系,提出了非均匀有源层掺杂分布模型。该模型将有源层划分成A,B两层,分别用N_dA(y)和N_dB(y)函数描述A,B层的掺杂分布,分布函数表示为: 结合GaAs FET分析模型,完成了有源层理论分布的计算、器件直流I—V特性的计算以及器件其它参数的计算,以便实现最佳的有源层掺杂分布。结果表明:双层尖峰型有源层掺杂分布是制造高输出线性度GaAs功率MESFET理想的掺杂分布。根据分析结果,在器件制造中用VPE生长方法获得了这种掺杂分布的外延材料,并设计制造了总栅宽为1200μm的GaAs功率FET。器件的直流I—V特性与理论分析结果相吻合,与均匀掺杂分布的器件相比较,实验器件的输出线性度得到了明显的改善,获得了良好的微波性能。微波性能测试结果为:
In order to improve the output linearity of the GaAs power MESFET, the improvement of the doping profile of the active layer of the device is an effective method. This paper explores the relationship between the active layer doping profile and the device output linearity, and proposes a non-uniform active layer doping profile. The model divides the active layer into A and B layers and describes the doping distributions of A and B layers respectively by N_dA (y) and N_dB (y) functions. The distribution function is expressed as follows: In combination with the GaAs FET analysis model, Calculation of the theoretical distribution of the source layer, calculation of the I-V characteristics of the device DC, and calculation of other parameters of the device in order to achieve the best active layer doping distribution. The results show that the doubly-doped active layer doping distribution is an ideal doping distribution for manufacturing high output linearity GaAs power MESFETs. According to the results of the analysis, this doping epitaxial material was obtained by VPE growth in the device fabrication, and a GaAs power FET with a total gate width of 1200 μm was designed and fabricated. The DC I-V characteristic of the device agrees well with the theoretical analysis. Compared with the uniform doping distribution device, the output linearity of the experimental device is obviously improved, and the good microwave performance is obtained. Microwave performance test results are: