Photoemission study of energy-band alignments and gap-state density distributions for high-k gate dielectrics

2001 ◽  
Vol 19 (6) ◽  
pp. 2212 ◽  
Author(s):  
Seiichi Miyazaki
Keyword(s):  
Energy Band ◽  
Gate Dielectrics ◽  
State Density ◽  
Density Distributions ◽  
High K ◽  
Band Alignments ◽  
Photoemission Study ◽  
Gap State

Band Alignments of High-K Dielectrics on Si and Pt

1999 ◽  
Vol 592 ◽  
Author(s):  
J Robertson ◽  
E Riassi ◽  
J-P Maria ◽  
A I Kingon
Keyword(s):  
Conduction Band ◽  
Gate Dielectrics ◽  
Random Access ◽  
Leakage Currents ◽  
Band Offsets ◽  
Silicon Devices ◽  
High K ◽  
Band Alignments ◽  
High K Materials ◽  
High Dielectric

ABSTRACTMaterials with a high dielectric constant (K) such as tantalum pentoxide (Ta2O5) and barium strontium titanate (BST) are needed for insulators in dynamic random access memory capacitors and as gate dielectrics in future silicon devices. The band offsets of these oxides must be over 1 eV for both electrons and holes, to minimise leakage currents due to Schottky emission. We have calculated the band alignments of many high K materials on Si and metals using the method of charge neutrality levels. Ta2O5 and BST have rather small conduction band offsets on Si, because the band alignments are quite asymmetric. Other wide gap materials Al2O3, Y2O3, ZrO2 and ZrSiO4 are found to have offsets of over 1.5 eV for both electrons and holes, suggesting that these are preferable dielectrics. Zirconates such as BaZrO3 have wider gaps than the titanates, but they still have rather low conduction band offsets on Si. The implications of the results for future generations of MOSFETs and DRAMS are discussed.

A PHOTOEMISSION STUDY OF THE ELECTRONIC STRUCTURE INDUCED BY POTASSIUM ADSORPTION ON TiO2(110)

1995 ◽  
Vol 02 (02) ◽  
pp. 147-152 ◽  
Author(s):  
RAINER HEISE ◽  
RALF COURTHS
Keyword(s):  
Electronic Structure ◽  
State Density ◽  
Photoemission Spectroscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Valence States ◽  
Weak Minimum ◽  
Photoemission Study ◽  
Gap States ◽  
Core Level Binding Energy ◽  
Gap State

Electronic structure effects induced by potassium adsorption up to one monolayer (ML) on a nearly stoichiometric TiO 2(110) surface has been studied by means of angle-resolved photoemission spectroscopy (ARUPS and ARXPS) from valence states and core levels. In agreement with the observations on K/TiO 2(100) [P.J. Hardman et al., Surf. Sci.269/270, 677 (1992)], potassium adsorption at room temperature leads—due to K-to-substrate charge transfer—to the reduction of surface Ti ions (to nominally Ti 3+ ions), evidenced by lowered Ti 2p core-level binding energy (ΔBE=–1.6 eV ) and occupation of Ti 3d-like band-gap states centered at 0.9 eV BE. The gap-state intensity exhibits a pronounced maximum at 0.37 ML coverage, where the work function has a weak minimum. This behavior is in agreement with a ionic-to-neutral transition of the K-substrate bonding with increasing K coverage, as suggested recently [Souda et al., Surf. Sci.285, 265 (1993)]. Annealing of a surface precovered with 0.27 ML potassium up to 1000 K results in metallization of the surface, evidenced by (i) the occupation of a second gap-state centered at 0.4 BE and with a considerable state-density at the Fermi energy, and (ii) Ti 2p core-levels lowered by 3.2 eV in BE (nominally “ Ti 2+” ions). This dramatic reduction of the surface is healed out with complete desorption of potassium. A discussion in terms of desorption of KO x species and oxygen diffusion from the bulk to the surface is given.

High K gate dielectrics for the silicon industry

2002 ◽  
Author(s):  
L. Manchanda ◽  
B. Busch ◽  
M.L. Green ◽  
M. Morris ◽  
R.B. van Dover ◽  
...  
Keyword(s):  
Gate Dielectrics ◽  
High K

scholarly journals Energy band and spin-dependent many-body interactions in ferromagnetic Ni(110): A high-resolution angle-resolved photoemission study

2005 ◽  
Vol 72 (21) ◽  
Author(s):  
Mitsuharu Higashiguchi ◽  
Kenya Shimada ◽  
Keisuke Nishiura ◽  
Xiaoyu Cui ◽  
Hirofumi Namatame ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Band ◽  
Many Body ◽  
Photoemission Study ◽  
Many Body Interactions
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