Why Gallium Nitride?

The power semiconductor evolution started with germanium and selenium devices that succumbed to silicon types around the 1950s. Broader silicon usage stemmed from its improved physical properties combined with a large investment in manufacturing infrastructure and engineering. However, silicon power MOSFETs have not kept pace with evolutionary changes in the power electronics systems industry. The power electronics industry reached the theoretical limit of silicon MOSFETs and now must go to another semiconductor material whose perfromance matches today’s newer systems.  The new material is gallium nitride (GaN) a high electron mobility (HEMT) semiconductor, whaich is poised to usher in new power devices that are superior to the present state of the art. Although GaN is young in its life cycle, it will certainly see significant improvements in the years to come.

What nomenclature do GaN devices employ?
GaN transistors borrowed the same nomenclature as their silicon brethren: gate, drain and source, as shown Fig. 1. In addition, on-resistance and breakdown voltage of a GaN device have a similar meaning as their silicon counterparts. On-resistance (RDS(ON)) vs. gate-source voltage curves are similar to silicon MOSFETs. The temperature coefficient of GaN FETs on-resistance is similar o the silicon MOSFET as it is positive, but the magnitude is significantly less.


Fig. 1 - Enhancement mode GaN has a circuiut schematic similar to silicon MOSFETs with Gate (G), Drain (D), and Source (S).