Uni-directional GaN-on-Si MOSHEMTs with high reverse-blocking voltage based on nanostructured Schottky drain

In this work we present uni-directional GaN-on-Si MOSHEMTs with state-of-the-art reverse-blocking performance. We integrated tri-anode Schottky barrier diodes (SBDs) with slanted tri-gate field plates (FPs) as the drain electrode, and achieved a high reverse-blocking voltage (V-RB) of -759 +/- 37 V at 0.1 mu A/mm with grounded substrate. The hybrid Schottky drain did not degrade the ON-state performance when compared with conventional ohmic drain, and the turn-ON voltage (V-ON) was as small as 0.64 +/- 0.02 V. These results show the potential of GaN-on-Si transistors as high-performance uni-directional power switches, and open enormous opportunities for future highly integrated GaN power devices

In-Plane-Gate GaN Transistors for High-Power RF Applications

In-plane-gatefield-effect transistors (IPGFETs) offer an innovative device architecture in which the channel conductivity is modulated by the electric field from the 2D electron gas in the two adjacent in-plane gates, isolated by etched trenches. The planar nature of the gate electrode yields a huge reduction in parasitic gate capacitance, which can lead to much higher frequency. Moreover, the fabrication process for these devices is extremely simple and with inherently self-aligned gates. Here, we combine for the first time the promising architecture of IPGFETs with the exceptional properties of III-Nitrides, such as large carrier density and breakdown field, to reveal their enormous potential for high-power RF devices. AlGaN/GaN IPGFETs demonstrated large drain current up to 1.4 A/mm and transconductance up to 665 mS/mm, which are, respectively, nine times-and five times-larger than the best IPGFETs demonstrated in other semiconductors. These devices presented excellent gate control with ON-OFF ratio up to 10(7) along with ultra-low capacitances down to 0.7 aF, leading to an estimated f(T) up to 0.89 THz. Extremely large breakdown voltage of 500 V was observed despite their nanoscale dimensions, with small leakage current below 1 nA up to 300 V. These results reveal that III-Nitride IPGFETs offer a promising pathway for future terahertz devices delivering large output powers

High Performance Tri-gate GaN Power MOSHEMTs on Silicon Substrate

We demonstrate high-performance GaN power metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) on silicon substrate based on a nanowire tri-gate architecture. The common issue of partial removal of carriers by nanowire etching in GaN tri-gate transistors was resolved mainly by optimized tri-gate geometry, including filling factor and trench width. The tri-gate reduced the OFF-state leakage current (I-OFF) and the subthreshold slope, increased the ON/OFF ratio, and improved the breakdown voltage (V-BR) of the device. With a gate-to-drain separation (L-GD) of 5 mu m, the tri-gate MOSHEMTs exhibited V-BR of 792 V at I-OFF of 0.3 mu A/mm, along with a small specific ON-resistance (R-ON, (SP)) of 0.91 +/- 0.08 m Omega.cm(2). With L-GD of 15 mu m, hard V-BR of 1755 V at I-OFF of 45 mu A/mm with high soft V-BR of 1370 V at I-OFF = 1 mu A/mm were achieved, rendering excellent high power figure of merits (FOMs) up to 1.25 GW/cm(2). These results unveil the significant potential of nanostructured GaN transistors for future power applications

Monolithic integration of GaN-based NMOS digital logic gate circuits with E-mode power GaN MOSHEMTs

In this work, we demonstrate high-performance NMOS GaN-based logic gates including NOT, NAND, and NOR by integration of E/D-mode GaN MOSHEMTs on silicon substrates. The load-to-driver resistance ratio was optimized in these logic gates by using a multi-finger gate design of E-mode GaN MOSHEMT to increase the logic swing voltage and noise margins, and reduce the transition periods. State-of-the-art NMOS inverter was achieved with logic swing voltage of 4.93 V at a supply voltage of 5 V, low-input noise margin of 2.13 V and high-input noise margin of 2.2 V at room temperature. Excellent high temperature performance, at 300 C, was observed with a logic swing of 4.85 V, low-input noise margin of 1.85 V and high output noise margin of 2.2V. In addition, GaN-based NAND and NOR NMOS logic gates are reported for the first time with very good performance. Finally, the logic gates were monolithically integrated with high-voltage E-mode power transistors, which reveals a significant step forward towards monolithic integration of GaN power transistors with gate drivers

High-Voltage and Low-Leakage AlGaN/GaN Tri-Anode Schottky Diodes With Integrated Tri-Gate Transistors

We present AlGaN/GaN nanostructured Schottky barrier diodes (SBDs) on silicon substrate with high breakdown voltage (V-BR) and low reverse leakage current (I-R), based on a hybrid of tri-anode and tri-gate architectures. The fabricated SBDs presented a small turn-ON voltage (V-ON) of 0.76 +/- 0.05 V, since the tri-anode architecture formed direct Schottky contact to the 2-D electron gas (2DEG). The reverse characteristic was controlled electrostatically by an embedded tri-gate transistor, instead of relying only on the Schottky barrier. This resulted in low I-R below 10 and 100 nA/mm at large reverse biases up to 500 and 700 V, respectively. In addition, these devices exhibited record V-BR up to 1325 V at I-R of 1 mu A/mm, rendering an excellent high-power figure-of-merit (FOM) of 939 MW/cm(2) and demonstrating the significant potential of nanostructured GaN SBDs for future efficient power conversion

900 V Reverse-Blocking GaN-on-Si MOSHEMTs With a Hybrid Tri-Anode Schottky Drain

In this letter, we present high-performance GaN-on-Si metal-oxide-semiconductor high electron mobility transistors with record reverse-blocking (RB) capability. By replacing the conventional ohmic drain with a hybrid tri-anode Schottky drain, a high reverse breakdown voltage (V-B(R)) of -900 V was achieved (at 1 mu A/mm with grounded substrate), along with a small reverse leakage current (I-R) of similar to 20 nA/mm at -750 V. The devices also presented a small turn-ON voltage (V-ON) of 0.58 +/- 0.02 V, a small increase in forward voltage (Delta V-F) of similar to 0.8 V, a high ON/OFF ratio over 1010, and a high forward breakdown voltage (V-B(F)) of 800 V at 20 nA/mm with grounded substrate. These results demonstrate a new milestone for RB GaN transistors, and open enormous opportunities for integrated GaN power devices

Field Plate Design for Low Leakage Current in Lateral GaN Power Schottky Diodes: Role of the Pinch-Off Voltage

In this letter, we demonstrate a general model to reduce the reverse leakage current (I-R) in high-voltage AlGaN/GaN Schottky diodes (SBDs) by engineering the pinchoff voltage (V-p) of their field plates (FPs). The maximum voltage drop at the Schottky junction (V-SCH) in the OFF state can be significantly decreased by reducing vertical bar V-p vertical bar, which leads to a drastically diminished I-R. We used a tri-gate architecture as means to control V-p and, thus, I-R, as it offers great flexibility to engineer V-p compared with conventional schemes. vertical bar V-p vertical bar of SBDs with tri-gate FPs was reduced by decreasing the width of the nanowires, which led to a very small I-R, below 10 nA/mm under reverse biases up to 500 V, and an increase of over 800 V in soft breakdown voltage (V-BR) at 1 mu A/mm. These results reveal the importance of V-p in reducing I-R for SBDs, and unveil the potential of tri-gate structures as FPs for power devices