GaN Schottky Diode Wafer

Group III nitrides are typical wide bandgap semiconductor materials, among which gallium nitride (GaN), an excellent representative, has wide applications in the fields of optoelectronics and power electronics. Especially, the AlGaN/GaN structure can generate two-dimensional electron gas (2DEG) with high electron concentration and high electron mobility. Combined with the high critical electric field of GaN, power electronic devices based on AlGaN/GaN can have faster switching speed, lower conduction resistance, and higher breakdown voltage. They have broad potential applications in consumer electronics, automotive electronics, new energy, industrial motors, and even ultra-high voltage (UHV,>10 kV) electronics. Among these devices, power Schottky barrier diodes (SBDs) are particularly important and are one of the core devices in power conversion systems. PAM-XIAMEN can produce GaN Schottky diode for wireless power transmission, detailed epitaxial structure please refer to the specification table below:

1. GaN Schottky Diode Epi-Structure

PAM240219 – SBD

Epi layer	Material	Thickness	Composition
Capping layer	GaN	1~2nm
Barrier layer	AlxGaN1-xN	–	0.23<x<0.25
Spacer	AlN	–
Channel layer	i-GaN	–
Buffer layer	C doped layer	–
Substrate	6” HR Si (RMS < 0.5nm in 5x5um2)

 

2. About High Frequency GaN Schottky Barrier Diode

GaN Schottky diode exhibits excellent power processing capabilities in power electronics applications and multipliers due to its physical characteristics of wide bandgap and high breakdown electric field. Especially AlGaN/GaN diode exhibits excellent characteristics of high electron mobility and high electron density due to the presence of two-dimensional electron gas (2DEG), providing a wide range of applications for high-frequency and high-power devices. SBD is one of the most important components in microwave power transmission systems. However, the high-frequency performance of SBD requires a low turn-on voltage (Von) to reduce conduction loss, and a high cutoff frequency to increase operating frequency.

In addition, the cutoff frequency of SBD is limited by the product of Schottky diode capacitance and conduction resistance (Ron), so reducing the anode size cannot effectively increase the cutoff frequency. Traditional planar AlGaN/GaN SBDs suffer from high Von and large capacitance, while low Schottky barrier metals (TiN, Mo, W) can reduce Von, but are accompanied by a large reverse leakage current. The concave anode structure is an effective solution to avoid these two drawbacks due to the direct contact of 2DEG with the anode metal. Nevertheless, due to the parallel plate capacitance caused by the anode field plate and 2DEG, this design still has a large capacitance. Compared with the SBD with a concave anode structure, the capacitance of the transverse SBD can be further reduced. Moreover, due to the direct contact of charge carriers with the anode metal, the transverse p-GaN Schottky diode also has a lower Von.

3. Effect of Annealing on Electrical Performance of N-polar GaN Schottky Barrier Diodes

N-polar GaN thin films were grown using MOCVD, and N-polar GaN SBD devices were prepared through photolithography and metal deposition processes. Research focused on studying the effect of annealing process of Schottky contact metal on the electrical performance of SBD devices. The results indicate that annealing treatment is beneficial for increasing the Schottky barrier height, reducing the ideal factor and reverse leakage current density of SBD devices. This is mainly because annealing can reduce the interface state density between Schottky contact metal and N-polar GaN, increase the barrier height for electron emission from trap states, but too high annealing temperature will greatly increase the interface state density, seriously reducing the electrical performance of SBD devices. There is reason to believe that this work provides a feasible method for achieving high-quality Schottky contacts on N-polar GaN based HEMTs.

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