The influence of an AlOx film in-situ deposited on the GaAs-based HFETs properties

An in-situ deposited AlO
_x
layer has a great influence on the transistor properties. We recently published a comparison between an AlGaAs/InGaAs/GaAs HFET (without any passivation) and a passivated MOSHFET (AlO
_x
/AlGaAs/InGaAs/GaAs. This paper reports on properties of AlGaAs/GaAs transistors with an InGaAs channel passivated with an in-situ deposited AlO
_x
layer. Also, the effectiveness of the passivation is discussed. The influence of an thin AlO
_x
layer on properties of passivated HFET in comparison to the passivated MOSHFET and the unpassivated HFET was studied. The understanding of the functionality of the in-situ deposited layer in the passivation or modification of surface trapping states will contribute to the knowledge of GaAs surface potential control.