Gallium Nitride (GaN) High Power Electronics (FY11)

Author:

Kenneth A. Jones   Randy P. Tompkins   Michael A. Derenge  

Issue Date:

2012

Abstract(summary):

This report covers work done for the Director's Research Initiative (DSI) on Gallium Nitride (GaN) High Power Electronics (HPE) in which GaN devices are assessed in comparison to those fabricated from silicon carbide (SiC). We show that for low power applications (< 1500 V) GaN diodes should have a lower on-resistance, and therefore less loss, than their SiC counterparts because the critical breakdown field and electron mobility are larger. We expect this will also be true for HPE GaN high electron mobility transistors (HEMTs) compared to SiC metal-oxide-semiconductor field effect transistors (MOSFETs). Although a few GaN devices have been made that have properties that exceed those made from SiC, these devices cannot yet be manufactured. Our work suggests the dominant problem is contamination of the metal-organic chemical vapor deposition (MOCVD) films by the carbon in the trimethyl gallium (TMGa). We suggest a better alternative is to grow the films by hydride vapor phase epitaxy (HVPE), which requires that conducting GaN substrates be grown to reduce the on-resistance (RON·SP) for the back side diodes. We also show that dislocations appear to strongly affect diode properties such as the ideality factor, but their effect on the breakdown voltage appears to be a less significant problem than was previously thought.

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