Title :
Energy Distribution of Positive Charges in
pMOSFETs
Author :
Jigang Ma ; Zhang, Jian F. ; Zhigang Ji ; Benbakhti, Brahim ; Wei Zhang ; Mitard, J. ; Kaczer, Ben ; Groeseneken, Guido ; Hall, Sebastian ; Robertson, John ; Chalker, Paul
Author_Institution :
Sch. of Eng., Liverpool John Moores Univ., Liverpool, UK
Abstract :
The high hole mobility of Ge makes it a strong candidate for end of roadmap pMOSFETs and low interface states have been achieved for the Al2O3-GeO2-Ge gate-stack. This structure, however, suffers from significant negative bias temperature instability (NBTI), dominated by positive charge (PC) in Al2O3/GeO2. An in-depth understanding of the PCs will assist in the minimization of NBTI and the defect energy distribution will provide valuable information. The energy distribution also provides the effective charge density at a given surface potential, a key parameter required for simulating the impact of NBTI on device and circuit performance. For the first time, this letter reports the energy distribution of the PC in Al2O3/GeO2 on Ge. It is found that the energy density of the PC has a clear peak near Ge Ec at the interface and a relatively low level between Ec and Ev. Below Ev at the interface, it increases rapidly and screens 20% of the Vg rise.
Keywords :
MOSFET; aluminium compounds; germanium; germanium compounds; hole mobility; interface states; minimisation; negative bias temperature instability; Al2O3-GeO2-Ge; NBTI; charge density; defect energy distribution; energy density; gate-stack; hole mobility; interface states; minimization; negative bias temperature instability; pMOSFET; positive charges; Aluminum oxide; Interface states; Logic gates; Silicon; Stress; ${rm Al}_{2}{rm O}_{3}/{rm GeO}_{2}$; Ge pMOSFETs; NBTI; Positive charges; aging; energy distribution; reliability;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2013.2295516