Abstract
AlGaN/GaN high electron mobility transistors with a range of dual metal gate (DMG) lengths have been fabricated and studied. An improvement in transconductance up to 9% has been measured in the DMG devices in comparison to the conventional single metal gate devices. This is attributed to the distribution of the electric field under the gate region as a result of two gate metals. The drain induced barrier lowering is also suppressed using the sub-µm DMG devices, with a drain induced barrier lowering decrease of around 50% due to a potential shielding effect in the two-dimensional electron gas channel.
Highlights
AlGaN/GaN high electron mobility transistors (HEMTs) have been an area of increasing research in high frequency and high power applications
We demonstrate sub-μm dual metal gate (DMG) structures on AlGaN/GaN HEMTs with two different gate metals: titanium (Ti) and palladium (Pd), and study the electrical characteristics in comparison with conventional single metal gate (SMG) devices
VTH of the PdAu/TiAu DMG devices was less sensitive to the drain bias changes with a drain induced barrier lowering (DIBL) of 19 mV V−1 when subjected to the same drain bias range as shown in figure 3
Summary
AlGaN/GaN high electron mobility transistors (HEMTs) have been an area of increasing research in high frequency and high power applications. Voltage (VTH) changes with drain bias [6] This limits the output power, gain and efficiency of the short gate length AlGaN/GaN HEMTs for RF applications [7]. One approach to improve the device transconductance and suppress DIBL of the lateral HEMTs is to employ a dual metal gate (DMG) structure with different metal work functions (WF) [9,10,11]. Simulations of GaN-based HEMT devices using this structure have been performed previously [12, 13] showing notable improvements in the electron velocity under the gate leading to a higher output current and transconductance as well as suppression in the DIBL in these devices [14]. A device simulation study was undertaken to understand the properties of the DMG HEMTs
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