Comparative assessment of InGaAs sub-channel and InAs composite channel double gate (DG)-HEMT for sub-millimeter wave applications

This work analyses the impact of channel material, channel thickness (TCH) and gate length (Lg) on the various performance device metrics of Double-gate (DG) High Electron Mobility Transistor (HEMT) by using 2D Sentaurus TCAD simulation. A comparison between In0.53Ga0.47As/In0.7Ga0.3As/In0.53Ga0.47As sub-channel and In0.7Ga0.3As/InAs/In0.7Ga0.3As composite channel DG-HEMT along with SG-HEMT is made by characterizing the device with structural and geometrical parameters suitable for applications requiring high frequency operations. The DG-In0.53Ga0.7As/In0.7Ga0.3As/In0.53Ga0.7As sub-channel/DG-In0.7Ga0.3As/InAs/In0.7Ga0.3As composite channel HEMT with channel thickness of 13 nm and barrier thickness (TB) of 2 nm with Lg = 30 nm are seen offering a positive threshold voltage (VT) of 0.298/0.21 V, transconductance (gm) of 3.09/3.3 mS/µm, with cut-off frequency (fT) and maximum oscillation frequency (fmax) of 776/788 GHz and 905/978 GHz, respectively at Vds = 0.5 V is obtained. If the channel thickness of the DG-InAs composite channel device is scaled and reduced to 10 nm, the RF performances are further enhanced to 809 GHz (fT) and 1030 GHz (fmax). Compared to DG-InGaAs sub-channel device, the device with thin DG-InAs composite channel device shows a better performance in terms of drain current (Ids), analog/RF performance thereby making it preferable for future THz applications.