Gallium nitride (GaN)-based vertical power Schottky barrier diode (SBD) has demonstrated outstanding features in high-frequency and high-power applications. This paper reviews recent progress on GaN-based vertical power SBDs, including the following sections. First, the benchmark for GaN vertical SBDs with different substrates (Si, sapphire, and GaN) are presented. Then, the latest progress in the edge terminal techniques are discussed. Finally, a typical fabrication flow of vertical GaN SBDs is also illustrated briefly.

The optimization of mesa etch for a quasi-vertical gallium nitride (GaN) Schottky barrier diode (SBD) by inductively coupled plasma (ICP) etching was comprehensively investigated in this work, including selection of the etching mask, ICP power, radio frequency (RF) power, ratio of mixed gas, flow rate, and chamber pressure, etc. In particular, the microtrench at the bottom corner of the mesa sidewall was eliminated by a combination of ICP dry etching and tetramethylammonium hydroxide (TMAH) wet treatment. Finally, a highly anisotropic profile of the mesa sidewall was realized by using the optimized etch recipe, and a quasi-vertical GaN SBD was demonstrated, achieving a low reverse current density of 10−8 A/cm2 at −10 V.

In this brief, a high-performance quasi-vertical GaN Schottky barrier diode (SBD) on sapphire substrate with post-mesa nitridation process is reported, featuring a low damaged sidewall with extremely low leakage current. The fabricated SBD with a drift layer of 1 μm has achieved a very high ON/OFF current ratio (I ON /I OFF ) of 10 12 with a low leakage current of ∼10 −9 A/cm 2 @-10 V, high forward current density of 5.2 kA/cm 2 at 3 V in dc, a low differential specific ON-resistance (R ON,sp ) of 0.3 m•cm 2 , and ideality factor of 1.04. In addition, a transmission-line-pulse (TLP) I-V test was carried out and 53 kA/cm 2 at 30 V in pulsed measurement was obtained without device failure, exhibiting a great potential for high power applications.

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In this study, novel AlGaN/GaN Schottky barrier diodes (SBDs) are fabricated with thin-barrier (5 nm) AlGaN/GaN heterostructures, featuring recess-free technology, eliminating bombardment plasma damage, and leading to high device uniformity. Combining a gated-edge termination (GET) design and assistance with high-quality low-pressure chemical vapor deposition SiN x , a low reverse leakage current (∼10 nA mm −1 @−600 V) and a high reverse breakdown voltage of over 1.78 kV (@1 µA mm −1 ) are obtained. At the same time, we achieve a low turn-on voltage of 0.57 V and a low differential on-state resistance R on,sp of 1.49 mΩ cm 2 for thin-barrier GET SBDs with an anode-to-cathode distance (L AC ) of 15 µm, yielding a Baliga's figure of merit of 2120 MW cm −2 . Moreover, this proposed diode process flow is compatible with AlGaN/GaN high-electron-mobility transistors, which is promising for its integration in the smart GaN platform.

Gallium nitride (GaN) has attracted increased attention because of superior material properties, such as high electron saturation velocity and high electrical field strength, which are promising for high-power microwave applications. We report on a high-performance vertical GaN-based Schottky barrier diode (SBD) and its demonstration in a microwave power limiter for the first time. The fabricated SBD achieved a very low differential specific on-resistance (RON,sp) of 0.21 mΩ·cm2, attributed to the steep-mesa technology, which assists in reducing the spacing between the edge of the anode and cathode to 2 μm. Meanwhile, a low leakage current of ~10−9 A/cm2@−10 V, a high forward current density of 9.4 kA/cm2 at 3 V in DC, and an ideality factor of 1.04 were achieved. Scattering parameter measurements showed that the insertion loss (S21) was lower than −3 dB until 3 GHz. In addition, a microwave power limiter circuit with two anti-parallel diodes was built and measured on an alumina substrate. The input power level reached 40 dBm (10 watts) in continuous-wave mode at 2 GHz, with a corresponding leakage power of 27.2 dBm (0.5 watts) at the output port of the limiter, exhibiting the great potential of GaN SBD in microwave power limiters.

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