Impact of oxygen supply during growth on the electrical properties of crystalline Gd2O3 thin films on Si(001)

Abstract

We investigated the influence of additional oxygen supply and temperature during the growth of thin Gd2O3 layers on Si(001) with molecular beam epitaxy. Additional oxygen supply during growth improves the dielectric properties significantly; however, too high oxygen partial pressures lead to an increase in the lower permittivity interfacial layer thickness. The growth temperature mainly influences the dielectric gate stack properties due to changes of the Gd2O3∕Si interface structure. Optimized conditions (600°C and pO2=5×10−7mbar) were found to achieve equivalent oxide thickness values below 1nm accompanied by leakage current densities below 1mA∕cm2 at 1V.

Atomic Layer Deposition of Gadolinium Aluminate using Gd(iPrCp)3, TMA, and O3 or H2O

“…Capacitance/voltage (C-V) data of metal-insulator-semiconductor (MIS) capacitors with 12.5 AE 0.5 nm thick Gd x Al 2- The permittivity was found to increase with Gd content, in keeping with the permittivity values reported for Al 2 O 3 (k $ 8) [42] and Gd 2 O 3 (typically 14-16, [18,19,25,43,44] although higher values up to 24 have also been reported for epitaxial layers [45] [12,13,46] where no large decrease of Full Paper the permittivity with respect to La 2 O 3 was also observed, neither due to Al 2 O 3 incorporation [47] nor due to amorphization. [48] 3.…”

Enhanced dielectric properties of nitrogen doped epitaxial Gd2O3 thin films on Si

“…The gap states which are strongly localized on the orbitals of the adjacent metal ions can result in significant increase in the leakage current conduction [18,28]. Further, if the V Os related defect states give rise to mobile oxide charges, they can result in flat band instability causing hysteretic C-V behaviour when a MOS capacitor is subjected to an external electric field [13]. One way of reducing the V Os in complex oxides is to grow the oxide thin films at sufficiently high 2 O P [13,29].…”

“…Further, if the V Os related defect states give rise to mobile oxide charges, they can result in flat band instability causing hysteretic C-V behaviour when a MOS capacitor is subjected to an external electric field [13]. One way of reducing the V Os in complex oxides is to grow the oxide thin films at sufficiently high 2 O P [13,29]. However, our experiments indicated that increasing 2 O P beyond ~5-8×10 -7 mbar does not significantly improve the dielectric properties, which could be related to the incomplete annihilation of V Os by increasing oxygen chemical potential [30].…”

“…It has been demonstrated in case of molecular beam epitaxy (MBE) grown LnO thin films that additional oxygen supply during growth often facilitates reduction of V Os [9,13]. However, continuous increase in the oxygen partial pressure ( which have been attempted to compensate such defects, often degrade the dielectric properties of such heterostructures due to the formation of an interfacial layer with lower κ values [14,15].…”

Crystalline Nanoscale M<SUB>2</SUB>O<SUB>3</SUB> (M=Gd, Nd) Thin Films Grown by Molecular Beam Epitaxy on Si(111)

“…During the layer growth, additional molecular oxygen was supplied into the chamber due to the oxygen deficiency in the rare-earth oxides evaporated by electron beam. 9,10) The substrate temperature was set to 948 K and the partial pressure of oxygen was kept at 5 Â 10 À7 mbar, which was controlled by a piezo leak valve. Crystal structures of the grown oxides were examined along the out-of-plane, in-plane, and asymmetric reciprocal space directions, as schematically shown in Fig.…”