Publications

M/A-COM Technology Solutions has continuing joint development efforts sponsored by the Department of Energy with MIT main campus and MIT Lincoln Laboratory to develop GaN-on-silicon two and three-terminal high-voltage/high current switching devices. The initial developmental goals were for a Schottky diode that has a reverse breakdown blocking voltage of >600 volts and is capable of handling 10 amperes of forward current. A comparison of the M/A-COM Technology Solutions lateral GaN Schottky diode on-resistance as a function of reverse breakdown voltage for a number of both lateral and vertical GaN Schottky diode geometries taken from the literature is presented. The substrates employed for all of these data points are either sapphire, SiC, silicon, and even one study which utilized single crystal GaN. Also included in this plot are theoretical limits for the basic materials typically used in GaN Schottky diode construction. It can be seen that the reverse breakdown results of approximately 1500 volts for M/A/-COM Technology Solutions lateral anode connected field GaN Schottky diodes on silicon substrates compare extremely favorably with the reported performance of the state-of-the-art devices, regardless of substrate material or design geometry.

M/A-COM Technology Solutions has continued in the joint development efforts sponsored by the Department of Energy with MIT main campus amd MIT Lincoln Labs to develop GaN on silicon three terminal high voltage/high current HEMT switching devices. The first year developmental goals were for a three terminal structure that has a reverse breakdown characteristic of >1200 V and is capable of switching 10 amperes of current. An average three terminal breakown of 1322 V was achieved on a single finger 250 um GaN on silicon HEMT device utilizing a source connected field plate with a 4.5 um drain region overlap. An individual device breakdown on a single finger 250 um GaN on silicon HEMT device with a SCFP of >1630 V was measured at a current of 250 uA (1mA/mm) - One of the highest yet reported for GaN on silicon in the industry.

Polycrystalline, partially epitaxial Sc2O3 films were grown on AlGaN/GaN substrates by atomic layer deposition (ALD). With this ALD Sc2O3 film as the insulator layer, the Sc2O3/AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors showed excellent electrical performance with a high Ion/Ioff ratio of over 108 and a low subthreshold slope of 75 mV/dec. The UV/NH4OH surface treatment on AlGaN/GaN prior to ALD was found to be critical for achieving these excellent figures. In addition, the Sc2O3 dielectric is found to be negatively charged, which facilitates the enhancement-mode operation. While bare Sc2O3 suffers from moisture degradation, depositing a moisture blocking layer of ALD Al2O3 can effectively eliminate this effect.