No abstract

Stress voltages on time-dependent breakdown characteristics of GaN MIS-HEMTs during negative gate bias stress (with V GS < 0, V D = V S = 0) and off-state stress (V G < V Th, V DS > 0, V S = 0) are investigated. For negative bias stress, the breakdown time distribution (β) decreases with the increasing negative gate voltage, while β is larger for higher drain voltage at off-state stress. Two humps in the time-dependent gate leakage occurred under both breakdown conditions, which can be ascribed to the dielectric breakdown triggered earlier and followed by the GaN layer breakdown. Combining the electric distribution from simulation and long-term monitoring of electric parameter, the peak electric fields under the gate edges at source and drain sides are confirmed as the main formation locations for per-location paths during negative gate voltage stress and off-state stress, respectively.

No abstract

The impact of carbon doping on the background carrier conduction in GaN has been investigated. It is found that the incorporation of carbon can effectively suppress the n-type background carrier concentration as expected. Moreover, from the fitting of the temperature-dependent carrier concentration and mobility, it is observed that high nitrogen-vacancy (V N ) dominates the background carrier at room temperature which consequently results in n-type conduction. The doping agent (carbon atom) occupies the nitrogen site of GaN and forms C N deep acceptor as revealed from photoluminescence. Besides, a relatively low hole concentration is ionized at room temperature which was insufficient for the compensation of n-type background carriers. Therefore, we concluded that this background carrier concentration can be suppressed by carbon doping, which substitutes the N site of GaN and finally decreases the V N .

No abstract