Integration of Gate Recessing and In Situ Cl- Doped Al2O3 for Enhancement-Mode AlGaN/GaN MOSHEMTs Fabrication

This letter demonstrates an integration process of in situ Cl- doped Al2O3 and gate recess technique to fabricate the enhancement mode AlGaN/GaN MOSHEMTs. The Cl- doped Al2O3 thin film is deposited by the ultrasonic spray pyrolysis deposition and characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The relative permittivity of Cl- doped Al2O3 is higher than the pure Al2O3 and the output current is enhanced. The threshold voltage of the enhancement mode AlGaN/GaN MOSHEMT with the Cl- doped Al2O3 gate dielectric layer rose from 0.2 to 1.3 V. Furthermore, the breakdown voltage of present enhancement mode AlGaN/GaN MOSHEMT reached 650 V. It was also found that the MOSHEMT with Cl- doped Al2O3 has higher gate leakage than that with pure Al2O3. The thermal stability of threshold voltage and current collapse phenomenon is described in this letter.