My research exploits the impacts, benefits and degradation, from critical processing steps for fabricating power devices, such as gate recess etch and Fluorine (F) treatment commonly used to obtain Enhancement-mode GaN HEMTs and MOS-HEMTs.

The device structure and the TEM picture of GaN MOS-HEMTs

X. Sun , et al IEDM 2014/Y. Zhang, et al APL 103, 033524 (2013)

The notorious donor trap at the top interface of the AlGaN layer is suppressed with a lose dose F treatment

 

F plasma increases Vth of GaN MOS-HEMT, however causing degradation of on-current and SS

 

The degradation induced by F plasma is multifaceted:

a. Interface degradation with an increasing F dose:

b. F-induced border traps in AlGaN by the ac-transconductance method

c. GaN over-etch under a high F dose that results in a serious drain current degradation