势垒层Al组分呈台阶梯度的AlGaN/GaN异质结构场效应晶体管

AlGaN/GaN Heterostructure Field Effect Transistor with Step Gradient Al Composition in Barrier Layer

设计并制备了AlGaN势垒层中Al组分呈线性梯度分布和呈台阶梯度分布的AlGaN/GaN结构材料及其异质结构场效应晶体管(HFET),测试了基于两种结构材料的HFET器件性能。分析发现,两种结构HFET的阈值电压分别为-9.5和-3.2 V,在1 V栅偏压下,峰值漏极电流密度分别达到684 mA/mm和600 mA/mm,峰值跨导分别达到102 mS/mm和167 mS/mm。通过分析随机半径上的峰值跨导分布发现,对于势垒层Al组分呈台阶梯度分布的AlGaN/GaN异质结构,由于每个AlGaN台阶层都是独立的,并且在外延过程中可以独立控制生长,其外延材料的方块电阻和HFET峰值跨导的相对标准偏差分别低至0.71%和0.7%,优于势垒层Al组分呈线性梯度分布的AlGaN/GaN结构及其HFET,这对后续规模化应用时的工艺控制和均匀性控制提供了便利。AlGaN/GaN台阶梯度异质结构的分层生长模式更有利于每层的独立优化。这种台阶梯度结构有望促进GaN器件在无线通信领域的规模化应用。

AlGaN/GaN structural materials and corresponding heterostructure field effect transistor(HFET) devices with linear gradient distribution and step gradient distribution of Al component in AlGaN barrier layer were designed and prepared,and the device performances of the HFETs based on the two structural materials were tested.Though the analysis,it is found that the threshold voltages of the HFETs based on the two structures are-9.5 and-3.2 V,respectively.Under 1 V gate bias voltage,the peak drain current densities reach 684 and 600 mA/mm respectively,and the peak transconductances reache 102 and 167 mS/mm respectively.By analyzing the peak transconductance distribution on the random radius,it is found that for the AlGaN/GaN heterostructure with step gradient distribution of Al composition in the barrier layer,each AlGaN step layer is independent and can be controllably and independently grown in the epitaxial process,so the relative standard deviations of the square resistance of the epitaxial material and peak transconductance of the HFET are as low as 0.71% and 0.7%,respectively,which are superior to those of the AlGaN/GaN structure with linear gradient distribution of Al component in the barrier layer and corresponding HFET,providing convenience for process control and uniformity control in subsequent large-scale application.The layered growth mode of the AlGaN/GaN step gradient heterostructure is more conducive to the independent optimization of each layer.The step gradient structure is expected to promote the large-scale application of GaN devices in the field of wireless communication.