Hou-Yu Wang

Electrical characterization of a gate-recessed AlGaN/GaN high-electron-mobility transistor with a p-GaN passivation layer

A novel passivation technique was developed that reduces the electron-surface-hopping-induced leakage current of AlGaN/GaN high-electron-mobility transistors (HEMTs) and enhances their electrical properties under high drain bias operation. The key aspect of this passivation technique entailed growing a p-type GaN layer on a traditional depletion-mode AlGaN/GaN HEMT; this p-GaN passivation layer was also used as the spacer layer of a field-plate metal. The originally exposed gate-to-source and gate-to-drain areas were passivated by the p-GaN cap layer. Thus, a surface depletion region was formed between the p-GaN passivation layer and an n-type AlGaN/GaN two-dimensional electron gas channel. This extra surface depletion region depleted the channel carriers far from the surface to reduce the probability of the carriers being trapped by surface defects. Therefore, the carrier-hopping-induced leakage current in the gate-to-drain area, which was strongly temperature-dependent, was suppressed. Low-frequency noi...

Temperature dependency and reliability of through substrate via InAlN/GaN high electron mobility transistors as determined using low frequency noise measurement

The reliability of a InAlN/GaN/Si high electron mobility transistor device was studied using low frequency noise measurements under various stress conditions. By applying the through substrate via (TSV) technology beneath the active region of the device, buffer/transition layer trapping caused by the GaN/Si lattice mismatch was suppressed. In addition, a backside SiO2/Al heat sink material improved thermal stability and eliminated the vertical leakage current of the proposed device. Applying the TSV technology improved the subthreshold swing slope from 260 to 230 mV/dec, owing to the stronger channel modulation ability and reduced leakage current of the device. The latticed-matched InAlN/GaN heterostructure had a stable performance after high current operation stress. The suppression of buffer/transition layer traps of the TSV device is a dominant factor in device reliability after long-term high-electric-field stress.