Simulation Study on Frequency Characteristics of AlN/β-Ga2O3 HEMT
The influence of frequency characteristics of devices is complex.The effects of AlN barrier thickness,gate length,gate-drain spacing and work function on the frequency characteristics of AlN/β-Ga2O3 high electron mobility transistor(HEMT)were studied by Sentaurus TCAD in this paper.The following conclusions are obtained:as the thickness of the AlN barrier layer increases from 10 nm to 25 nm,the cutoff frequency(fT)and maximum oscillation frequency(fmax)rise by 18 and 17 GHz respectively.The decrease of gate capacitance is the main reason for the increase of fT.Furthermore,it was found that the thinner barrier layer enhanced the gate's ability to control the channel electrons.When the gate length is scaled down from 0.9 µm to 0.1 μm,fT and fmax increase by 84 and 98 GHz,respectively,representing a far more profound influence on frequency characteristics than the barrier layer thickness.However,when the gate length fell below 0.1 μm,short-channel effects emerged.As the gate-drain spacing increase,fT exhibits a slight decrease.Coupled with the concurrent reduction in source resistance,this led to a synchronized trend in fmax and fT only when the gate-source voltage(VGS)exceeds-1.2 V.The work function,on the other hand,has minimal impacts on fT and fmax,but an increase in the work function positively influenced the device's pinch-off characteristics.In summary,this paper indicates that by shortening the gate length while concurrently augmenting the thickness of the AlN barrier layer,gate-drain spacing,and work function,one can enhance the frequency characteristics while also improving the pinch-off characteristics of the device,which has certain guiding significance for the design of HEMT devices.
β-Ga2O3AlNHEMTcutoff frequencymaximum oscillation frequency
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