Robust SiNx/GaN MIS-HEMTs With Crystalline Interfacial Layer Using Hollow Cathode PEALD

초록

In this letter, we report gallium nitride-based metal-insulator-semiconductor high-electron-mobility transistors (GaN MIS-HEMTs) with a 16-nm-thick silicon nitride (SiNx) gate insulator and surface passivation layer grown using low-temperature (300 degrees C) hollow cathode plasma-enhanced atomic layer deposition. Tris(dimethylamino) silane and a remote N-2 plasma were used as the silicon precursor and the nitrogen co-reactant, respectively. Though the growth temperature was as low as 300 degrees C, we obtained excellent film properties such as a high refractive index (2.00), a high film density (2.9 g/cm(3)), and a low wet etch rate (0.8 nm/min) in 100: 1 hydrofluoric acid. High-resolution transmission electronmicroscopyimages of the gate stacks showed similar to 1.5 nm beta-phase Si3N4 crystalline interfacial layer on the GaN surface. The devices showed a negligible hysteresis of similar to 50mV, a steep subthreshold slope of 76mV/dec, and a high ON/OFF drain current ratio of similar to 10(9). In addition, the devices showed a small positive/negative bias temperature threshold voltage (V-th) instability (similar to V-th similar to 0.2 V at 25 degrees C and 150 degrees C) as well as a mitigated current collapse under an off-state quiescent V-DS of 20 V.

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