Research of Trap and Electron Density Distributions in the Interface of Polyimide/Al2O3 Nanocomposite Films Based on IDC and SAXS

The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS） tests. According to the electron density distribution for quasi two-phase mixture doped by spherical nanoparticles, the electron densities in the interfaces of PI/Al2O3 nanocomposite films are evaluated. The trap level density and carrier mobility in the interface are studied. The experimental results show that the distribution and the change rate of the electron density in the three layers of interface are different, indicating different trap distributions in the interface layers. There is a maximum trap level density in the second layer, where the maximum trap level density for the nanocomposite film doped by 25 wt% is 1.054 × 10^22 eV·m^-3 at 1.324eV, resulting in the carrier mobility reducing. In addition, both the thickness and the electron density of the nanocomposite film interface increase with the addition of the doped Al2O3 contents. Through the study on the trap level distribution in the interface, it is possible to further analyze the insulation mechanism and to improve the performance of nano-dielectric materials.

Influence of ultra-thin TiN thickness(1.4 nm and 2.4 nm) on positive bias temperature instability(PBTI)of high-k/metal gate nMOSFETs with gate-last process

The positive bias temperature instability（PBTI） degradations of high-k/metal gate（HK/MG） n MOSFETs with thin TiN capping layers（1.4 nm and 2.4 nm） are systemically investigated. In this paper, the trap energy distribution in gate stack during PBTI stress is extracted by using ramped recovery stress, and the temperature dependences of PBTI（90℃,125℃, 160℃） are studied and activation energy（Ea） values（0.13 eV and 0.15 eV） are extracted. Although the equivalent oxide thickness（EOT） values of two TiN thickness values are almost similar（0.85 nm and 0.87 nm）, the 2.4-nm TiN one（thicker Ti N capping layer） shows better PBTI reliability（13.41% at 0.9 V, 90℃, 1000 s）. This is due to the better interfacial layer/high-k（IL/HK） interface, and HK bulk states exhibited through extracting activation energy and trap energy distribution in the high-k layer.

A novel modified charge pumping method for trapped charge characterization in nanometer-scale devices

A new modified method based on the charge pumping technique is proposed and adopted to extract the lateral profiles of oxide charges in an advanced MOSFET. A 0.12 μm SONOS device with 50 nm threshold voltage peak is designed and utilized to demonstrate the proposed method. The trapped charge distribution with a narrow peak can be precisely characterized with this method, which shows good consistency with the measured threshold voltage.

Thermally stable photoluminescence and long persistent luminescence of Ca3Ga4O9:Tb^3+/Zn^2+

A green long persistent luminescence（LPL） phosphor Ca3Ga4O9：Tb3＋/Zn2＋ was prepared. Ca3 Ga4 O9 matrix exhibits blue self-activated LPL due to the creation of intrinsic traps. When Tb3＋ is doped, the photoluminescence（PL） and LPL colors change from blue to green with their intensities significantly enhanced. The doping of Zn^（2＋） evidently improves the PL and LPL performances of the Ca3Ga4O9 matrix and Ca3Ga4O9：Tb^（3＋）. The thermoluminescence（TL） spectra show that a successive trap distribution is formed by multiple intrinsic traps with different depths in the Ca3 Ga4 O9 matrix, and the incorporation of Tb^（3＋） and Zn^（2＋） effectively increases the densities of these intrinsic traps. The existence of a successive trap distribution makes the Ca3 Ga4 O9：Tb^（3＋）/Zn^（2＋） phosphor exhibit thermally stable PL and LPL, It is indicated that this phosphor shows great promise for the application such as high-temperature LPL phosphor.

Bright yellow-emitting long persistent luminescence from Mn^(2+)-activated strontium aluminate phosphor

We developed bright yellow-emitting long persistent luminescence(LPL)materials Sr_(4)Al_(14)O_(25):Mn^(2+)and Sr_(4)Al_(14)O_(25):Mn^(2+),N(N=Zr^(4+),Ho^(3+),Er^(3+))by high temperature solid-state reaction.The addition of Zr^(4+),Ho^(3+)and Er^(3+)can regulate trap distributions and improve energy storage ability of the materials.The LPL perfo rmance of SAO:Mn^(2+),Ho^(3+)is optimal,considering LPL intensity and duration time.Bright LPL of SAO:Mn^(2+),Ho^(3+)can be observed for 3 h by naked eyes in dark after removing the excitation source.Profiles of LPL spectra are different from those of PL,because the two types of Mn^(2+)centers do not play equal parts in LPL and photoluminescence(PL).Trap depths of TL peaks centered at 354 K(peak 1)and 455 K(peak 2)are 0.60 and 0.72 eV,respectively.And peak 1 at 354 K is the effective TL peak responsible for LPL.In SAO:Mn^(2+),Ho^(3+),Mn^(2+)ions doped in Al^(3+)sites serve as emitting centers,and positively charged HoSr defects are the main effective trap centers.Finally,a feasible LPL mechanism of SAO:Mn^(2+),Ho^(3+)was proposed to clarify the generation process of LPL.

A physical surface-potential-based drain current model for polysilicon thin-film transistors

A physical drain current model of polysilicon thin-film transistors based on the charge-sheet model, the density of trap states and surface potential is proposed.The model uses non-iterative calculations,which are single-piece and valid in all operation regions above flat-band voltage.The distribution of the trap states,including both Gaussian deep-level states and exponential band-tail states,is also taken into account,and parameter extraction of trap state distribution is developed by the optoelectronic modulation spectroscopy measurement method. Comparisons with the available experimental data are accomplished,and good agreements are obtained.