掺杂AlGaN/GaN HEMT电流崩塌效应研究

对不同掺杂浓度AlGaN/GaN HEMTs施加直流偏置应力,研究掺杂AlGaN/GaN HEMTs电流崩塌效应.实验表明,掺杂AlGaN势垒层对器件电流崩塌效应有明显的抑制作用,随着掺杂浓度增加,掺杂对电流崩塌效应的抑制作用越显著.这是因为对于掺杂AlGaN/GaN HEMT,表面态俘获电子将耗尽掺杂AlGaN层,从而能对2DEG起屏蔽作用.AlGaN体内杂质电离后留下正电荷也能进一步屏蔽表面态对沟道2DEG的影响.

A Study on Current Collapse Effect in Doped AlGaN/GaN HEMTs

Current collapse in doped AlGaN/GaN HEMTs has been studied by applying DC bias stress to devices with various doped layer structures,including undoped layer structure.It has been demonstrated that current collapse effect was suppressed effectively in doped structures.And the suppressed effect was more obviously with the increasing of doping concentration.The positive dependence of doping AlGaN layer is due to surface potential fluctuations modulate the doped layer instead of the channel with the doped layer.On the other hand,the positive charges in doped AlGaN layer protect the 2DEG channel from the surface state between metal gate and drain,which capture electrons and form floating gate.