Characteristics of InxAl1-xN-GaN high-electron mobility field-effect transistor

GaN-based field effect transistors commonly include an AlxGa1-xN barrier layer for confinement of a two-dimensional electron gas (2DEG) in the barrier/GaN interface. Some of the limitations of the AlxGa1-xN-GaN heterostructure can be, in principle, avoided by the use of InxAl1-xN as an alternative barrier, which adds flexibility to the engineering of the polarization-induced charges by using tensile or compressive strain through varying the value of x. Here, the implementation and electrical characterization of an InxAl1-x-GaN high electron mobility transistor with Indium content ranging from x = 0.04 to x = 0.15 is described. The measured 2DEG carrier concentration in the In0.04Al0.96N-GaN heterostructure reach 4 x 10(13) cm(-2) at room temperature, and Hall mobility is 480 and 750 cm(2)/V . s at 300 and 10 K, respectively. The increase of Indium content in the barrier results in a shift of the transistor threshold voltage and of the peak transconductance toward positive gate values, as well as a decrease in the drain current. This is consistent with the reduction in polarization difference between GaN and InxAl1-xN. Devices with a gate length of 0.7 mum exhibit f(t) and f(max) values of 13 and 11 GHz, respectively.