Interface Defect Hydrogen Depassivation and Capacitance-Voltage Hysteresis of Al2O3/InGaAs Gate Stacks

Kechao Tang; Felix Roberto Palumbo; Liangliang Zhang; Ravi Droopad; Paul C McIntyre

doi:10.1021/acsami.6b16232

Interface Defect Hydrogen Depassivation and Capacitance-Voltage Hysteresis of Al₂O₃/InGaAs Gate Stacks

ACS Appl Mater Interfaces. 2017 Mar 1;9(8):7819-7825. doi: 10.1021/acsami.6b16232. Epub 2017 Feb 20.

Authors

Kechao Tang, Felix Roberto Palumbo^{1

2}, Liangliang Zhang, Ravi Droopad³, Paul C McIntyre

Affiliations

¹ National Scientific and Technical Research Council, CONICET/GAIANN-CNEA, Buenos Aires, Argentina.
² National Technological University, Buenos Aires, Argentina.
³ Ingram School of Engineering, Texas State University , San Marcos, Texas 78666, United States.

PMID: 28152310
DOI: 10.1021/acsami.6b16232

Abstract

We investigate the effects of pre- and postatomic layer deposition (ALD) defect passivation with hydrogen on the trap density and reliability of Al₂O₃/InGaAs gate stacks. Reliability is characterized by capacitance-voltage hysteresis measurements on samples prepared using different fabrication procedures and having different initial trap densities. Despite its beneficial capability to passivate both interface and border traps, a final forming gas (H₂/N₂) anneal (FGA) step is correlated with a significant hysteresis. This appears to be caused by hydrogen depassivation of defects in the gate stack under bias stress, supported by the observed bias stress-induced increase of interface trap density, and strong hydrogen isotope effects on the measured hysteresis. On the other hand, intentional air exposure of the InGaAs surface prior to Al₂O₃ ALD increases the initial interface trap density (D_it) but considerably lowers the hysteresis.

Keywords: Al2O3; InGaAs; MOSCAP; border traps; hydrogen depassivation; interface traps; reliability.