Browsing by Author "Chu, CM"

Now showing 1 - 4 of 4

A physical model for hole direct tunneling current in P+ poly-gate PMOSFETs with ultrathin gate oxides
(2000-11-01)
Yang, KN
;
Huang, HT
;
Chang, MC
;
Chu, CM
;
Chen, YS
A model of the hole direct tunneling gate current accounting for heavy and light hole's subbands in the quantized inversion layer is built explicitly. This model comprises four key physical parameters: inversion layer charge density, hole impact frequency on SiO2/Si interface, WKB transmission probability, and reflection correction factor. With the effective hole mass m(oxh) = 0.5m(o) for parabolic dispersion relationship in the oxide, experimental reproduction without any parameter adjustment is consistently achieved in p(+) poly-gate pMOSFETs with 1.23, 1.85, and 2.16 nm gate oxide thicknesses. The proposed model can thereby serve as a promising characterization means of direct tunnel oxides. In particular, it is calculated that the secondary subbands and beyond, although occupying few holes, indeed contribute substantially to the direct tunneling conduction due to effective lo,vcr barrier heights, and are prevailing over the first subbands for reducing oxide field down below 1 MV/cm.
Electrical properties and crystal structure of (Ba,Sr)TiO3 films prepared at low temperatures on a LaNiO3 electrode by radio-frequency magnetron sputtering
(1997-01-13)
Chu, CM
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba,Sr)TiO3 films on a LaNiO3 underlayer were prepared by radio-frequency magnetron sputter deposition. The onset of crystallization of the films occurred at a deposition temperature (T-d) as low as 200 degrees C. Good crystallinity was observed at T-d greater than or equal to 350 degrees C. A moderate high dielectric constant (epsilon(r) similar to 170-250) of the films was obtained at relatively low T-d similar to 200-360 degrees C. The value of epsilon(r) showed a much slower increase with T-d greater than or equal to 350 degrees C than that expected from the progress of crystallinity. The deviation was attributed to an interdiffusion layer formed between the him and underlayer, which also caused an abnormal contact potential barrier and a decline of the epsilon(r) value of the samples postannealed at 350 degrees C. Annealing at 300 degrees C under O-2 atmosphere lessened the oxygen deficiency in the film and enhanced the dielectric constant without forming an interfacial layer. (C) 1997 American Institute of Physics.
Electrical properties and crystal structure of (Ba,Sr)TiO3 films prepared at low temperatures on a LaNiO3 electrode by radio-frequency magnetron sputtering
(1997-01-13)
Chu, CM
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba,Sr)TiO3 films on a LaNiO3 underlayer were prepared by radio-frequency magnetron sputter deposition. The onset of crystallization of the films occurred at a deposition temperature (T-d) as low as 200 degrees C. Good crystallinity was observed at T-d greater than or equal to 350 degrees C. A moderate high dielectric constant (epsilon(r) similar to 170-250) of the films was obtained at relatively low T-d similar to 200-360 degrees C. The value of epsilon(r) showed a much slower increase with T-d greater than or equal to 350 degrees C than that expected from the progress of crystallinity. The deviation was attributed to an interdiffusion layer formed between the him and underlayer, which also caused an abnormal contact potential barrier and a decline of the epsilon(r) value of the samples postannealed at 350 degrees C. Annealing at 300 degrees C under O-2 atmosphere lessened the oxygen deficiency in the film and enhanced the dielectric constant without forming an interfacial layer. (C) 1997 American Institute of Physics.
Electrical properties and crystal structures of (Ba,Sr)TiO3 films and BaRuO3 bottom electrodes prepared by sputtering
(1998-03-09)
Chu, CM
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba,Sr)TiO3 (BST) films were synthesized on BaRuO3 (BRO) using radio-frequency magnetron sputter deposition. Conductive (similar to 1 m Omega cm) BRO layers of (110) texture were produced at a deposition temperature T-d = 400 degrees C, about 200 degrees C lower than that of SrRuO3. The BST (100 nm) deposited on the BRO showed a (110) preferred orientation and crystallization formation at temperatures as low as 200 degrees C. An interfacial layer and the local epitaxial growth of BST on BRO layers within columnar grains were confirmed by high-resolution transmission-electron microscopy studies. Uniform I-V characteristics (I < 1 x 10(-7) A/cm(2)) for bias voltages in the range 0.0-3.0 V of all the BST films deposited within T-d = 300-500 degrees C were observed. The dielectric constants of the BST films (e.g., epsilon(r) = 300 at T-d = 400 degrees C) are considerably higher than those generally achievable for the same T-d by using Pt bottom electrodes. The dependence of the annealing atmosphere (N-2 and O-2) Of the dielectric constants was studied and attributed to a diffused BST/BRO interfacial layer which is semiconductive in a reduced state and insulating in an oxidized state. (C) 1998 American Institute of Physics. [S0003-6951(98)01910-X].