April 20, 2017
Gallium (Ga) is a chemical element with atomic number 31. Gallium doesn’t exist freely in nature. Instead, it’s a byproduct in the production of zinc and aluminum.
The GaN compound is formed by gallium and nitrogen atoms arranged, most commonly, in a wurtzite crystal structure. The wurtzite crystal structure (shown in the figure below) is hexagonal and is characterized by two lattice constants (marked a and c in the figure).
The GaN crystal structure
In the semiconductor world, GaN is usually grown at a high temperature (approximately 1,100°C) by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) techniques on a foreign substrate (silicon carbide [SiC] for RF applications, or silicon [Si] for power electronics applications).
The GaN-on-SiC approach combines the high power density capabilities of GaN with the superior thermal conductivity and low RF losses of SiC. That’s why GaN-on-SiC is the combination of choice for high power density RF performance. Today, you can get GaN-on-SiC substrates up to 6 inches in diameter.
The GaN-on-Si combination has a much poorer thermal performance and higher RF losses but is much cheaper. That’s why GaN-on-Si is the combination of choice for price-sensitive power electronics applications. Today you can get GaN-on-Si substrates up to 8 inches in diameter.
GaN is a relatively new technology compared to other semiconductors, such as Si and GaAs, but it has become the technology of choice for high-RF, power-hungry applications like those required to transmit signals over long distances or at high-end power levels (such as radar, base transceiver stations [BTS], satellite communications, electronic warfare [EW], and so on).
GaN-on-SiC stands out in RF applications for several reasons:
To learn more about GaN, including the benefits of GaN’s high power density, download our e-book, GaN RF Technology For Dummies®.
– Excerpted with permission from John Wiley & Sons, Inc., from GaN RF Technology For Dummies.
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