SiC and GaN devices – wide bandgap is not all the same

Abstract

Silicon carbide (SiC)-diodes have been commercially available since 2001 and various SiC-switches have been launched recently. Parallelly, gallium nitride (GaN) is moving into power electronics and the first low-voltage devices are already on the market. Currently, it seems that GaN-transistors are ideal for high frequency ICs up to 1kV (maybe 2kV) and maximum a few 10A. SiC transistors are better suited for discrete devices or modules blocking 1kV and above and virtually no limit in the current but in that range they will face strong competition from the silicon insulated gate bipolar transistors (IGBTs). SiC and GaN Schottky-diodes would offer a similar performance, hence here it becomes apparent that material cost and quality will finally decide the commercial success of wide bandgap devices. Bulk GaN is still prohibitively expensive, whereas GaN on silicon would offer an unrivalled cost advantage. Devices made from the latter could be even cheaper than silicon devices. However, packaging is already a limiting factor for silicon devices even more so in exploiting the advantage of wide bandgap materials with respect to switching speed and high temperature operation. After all, reliability is a must for any device no matter which material it is made of.

Evaluation of lattice curvature and crystalline homogeneity for 2-inch GaN homo-epitaxial layer

“…10,11 Many GaN devices have been grown on other substrates, such as sapphire, Si, and SiC substrates, through hetero-epitaxial growth. [12][13][14][15] Layers of GaN grown by hetero-epitaxial methods feature a high defect density owing to lattice strain induced by the different lattice constants of the substrate and thin film. Although researchers have used buffer layers to reduce the lattice constant difference, charge trapping effects lower the electric performance and reproducibility of devices.…”

Comparative evaluation of the loss and thermal performance of advanced three level inverter topologies

“…While the Hybrid-NPC structure shows the same device count as the conventional Si T-Type structure. However, the increased device cost is caused by the more expensive SiC material compared to Si to date [24]. This is illustrated in Table IV which shows the device cost for the configurations as presented in this paper.…”

The Past, Present, and Future of Power Electronics Integration Technology in Motor Drives

“…While the idea of replacing silicon with silicon carbide in power electronics dates back to the 1950s, commercial development of WBG power semiconductors did not gain significant momentum until the 1990s [21]. Key motivations for using WBG materials instead of conventional silicon in power semiconductors are opportunities for significant advantages in the areas of operating temperature, efficiency, and switching frequencies.…”