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

Thin HfTiO_x high-k gate dielectric (Ti ∼26.6%) has been sputter-deposited on strained Si_0.81Ge_0.19 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 Si_0.81Ge_0.19 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 heterointerface. To better understand the conduction mechanism between the hetero-interface and temperature-dependent J–V, a calibrated TCAD simulation was carried out. (author)