Electrical measurements of voltage stressed Al2O3/GaAs MOSFET

Electrical characteristics of GaAs metal–oxide–semiconductor field effect transistor with atomic layer deposition deposited Al2O3 gate dielectric have been investigated. The IV characteristics were studied after various constant voltage stress (CVS) has been applied. A power law dependence of the gate leakage current (Ig) on the gate voltage (Vg) was found to fit the CVS data of the low positive Vg range. The percolation model well explains the degradation of Ig after a high positive Vg stress. A positive threshold voltage (Vth) shift for both +1.5 V and +2 V CVS was observed. Our data indicated that positive mobile charges may be first removed from the Al2O3 layer during the initial CVS, while the trapping of electrons by existing traps in the Al2O3 layer is responsible for the Vth shift during the subsequent CVS.