Electrical Properties of $\hbox{Ga}_{2}\hbox{O}_{3}/ \hbox{GaAs}$ Interfaces and GdGaO Dielectrics in GaAs-Based MOSFETs

Electrical properties of Ga 2 O 3 /GaAs interfaces with GdGaO cap dielectrics used in recent enhancement-mode GaAs-based NMOSFETs which perform in line with theoretical model predictions are presented. Capacitors with GdGaO thickness ranging from 3.0 to 18 nm (0.9 les EOT les 3.9 nm) have been characterized by capacitance-voltage measurements. Midgap interface state density D it , effective workfunction phi m , fixed charge Q f , dielectric constant kappa, and low field leakage current density are 2 times10 11 cm -2 middoteV -1 , 4.93 eV, -8.9 times10 11 cm -2 , 19.5, and 10 -9 - 10 -8 A/cm 2 , respectively. The presence of interfacial Gd was confirmed to dramatically degrade electrical interface properties. The data illuminate the intimate interplay between heterostructure and interface engineering to achieve optimum MOSFET operation.