Experimental and simulation study of charge transport mechanism in HfTiOx high-k gate dielectric on SiGe heterolayers

Thin HfTiOx high-k gate dielectric (Ti similar to 26.6%) has been sputter-deposited on strained Si0.81Ge0.19 heterolayers. The energy band discontinuities and interface properties were studied using X-ray photoelectron spectroscopy. The conduction band offset, and valance band offset between HfTiOx and Si0.81Ge0.19 were found to be 1.34 and 2.52 eV, respectively. Further, temperature-dependent (300-500 K) current density-voltage measurements (J-V) were utilized to explore the underlying leakage current conduction mechanism. The conductive dislocation and emission barrier heights at the hetero-interface have also been extracted from temperature-dependent J-V measurement. The barrier height of 1.22 to 2.02 eV for Schottky emission and 0.76 to 1.26 eV for Poole-Frenkel emission were estimated at the hetero-interface. To better understand the conduction mechanism between the hetero-interface and temperature-dependent J-V, a calibrated TCAD simulation was carried out.