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91.
采用k·p方法理论,考虑了极化电场和自由载流子重新分布等因素,通过薛定谔方程和泊松方程自洽求解得到InGaN/AlInGaN,InGaN/GaN,InGaN/InGaN,InGaN/AlGaN量子阱导带和价带的能带结构,并由此计算了不同量子阱结构的自发发射谱.分析对比发现AlInGaN材料特有的自发极化和压电极化效应在阱垒界面处形成的极化电荷对量子阱发光特性有重要的影响.以AlInGaN为垒,优化其中各元素的组分可以减小极化电场的影响,提高量子阱自发发射谱强度.同时,综合考虑了极化电荷和势垒高度的影响,提出了具体的优化方法,并给予了物理解释. 相似文献
92.
分析了阱宽、垒高和应变对量子阱材料TE模和TM模折射率的影响,并剖析了其中的物理机理.研究表明:对于量子限制效应带来的量子阱折射率偏振相关性,阱宽越小或垒高越高,折射率偏振相关性越大.压应变增大时,折射率偏振相关性增大,张应变可以克服量子限制效应带来的折射率偏振影响.对于不同阱宽和垒高的量子阱,均存在合适的张应变量使折射率偏振相关性最小,且阱宽越小或垒高越高所需的张应变量越大.根据以上分析,提出量子阱材料折射率低偏振相关设计方法,并据此设计出C波段(1 530~1 565 nm)内折射率低偏振相关(小于0.03)的量子阱材料In0.49Ga0.51As/In0.77Ga0.23As0.5P0.5.研究结果有助于优化设计光网络中关键器件. 相似文献
93.
Herein, a novel thin-film encapsulation for flexible organic light-emitting diodes (FOLEDs) is proposed, and its long-term reliability in tensile stress conditions was tested. The hybrid nano-stratified moisture barrier consists of 2.5 dyads of an Al2O3/ZnO nano-stratified structure and a S-H nanocomposite organic layer. The nano-stratified structure is prepared by low-temperature atomic layer deposition and the S-H nanocomposite by spin-coating at a thickness of 30 and 120 nm, respectively. An optical transmittance of 89.05% was measured with the 2.5-dyad hybrid nano-stratified moisture barrier with a total thickness of 330 nm. A low water vapor transmission rate (WVTR) of 1.91 × 10−5 g/m2day was recorded based on an electrical Ca test at 30 °C and 90% R.H. without losing its properties after a bending test. With this highly reliable hybrid nano-stratified moisture barrier, FOLEDs were successfully encapsulated. After 30 days under conditions of 30 °C and 90% R.H. with tensile stress, the J-V-L performances of the FOLEDs were comparable to those of the initial state without dark spots. These results suggest that this hybrid nano-stratified moisture barrier is an excellent method for encapsulating FOLEDs. 相似文献
94.
We studied silver barrier ohmic (Ni/AuGe/Ag/Au) contacts to the GaAs based HEMT structures and observed strong dependence
of the cleaning procedures on the ohmic con-tact resistance (Rc), its stability and reliability. The chemical profiles of the metal con-tacts before and after alloying were measured by
SIMS. Samples cleaned with the com-bined plasma O2 and NH4OH process exhibited excellent results:R
c ∼ 0.1–0.12 ohm-mm when alloyed in the temperature range of 440–540° C and remained stable when subjected to a 200° C and
600mA/mm stress condition for 1000 hr. 相似文献
95.
For high-density FeRAM memories, the 1T–1C architecture has been proposed. In this scheme, the ferrocapacitor (FeCAP), a metal\ferroelectric film\metal-like sandwich, is placed directly on top of polysilicon or tungsten plugs contacted to the underlying CMOS technology. Our ferroelectric material of choice, SrBi2Ta2O9 (SBT), requires crystallization anneals ranging from 650 to 800 °C in full oxygen. The bottom electrode (BE) needs to be conductive, as well as an oxygen barrier to protect the underlying plug from oxidation. We have developed a BE stack combination consisting of Pt/IrO2/Ir/Ti(Al)N. Each layer plays a critical role in the performance of the barrier. Issues such as thermal expansion, stress relaxation, grain growth, and oxidation can be critical in order to have a working bottom electrode. For capacitor formation, the complete stack is etched and covered by SBT. Since all layers are in contact with SBT, it is important to understand how the ferroelectric interacts with both the individual layers and the combined structure. In this paper, we will present our understanding of the chemical reactivity between SBT and the BE stack, which has been successfully engineered to prevent oxidation of the underlying plug. 相似文献
96.
4H-SiC Schottky barrier diodes (SBDs) were fabricated and characterized from room temperature to 573 K using HfNxBy as Schottky electrodes. The results are compared to SBDs fabricated using other electrodes that include Ni, Pt, Ti and Au. The Schottky barrier height Φb for as-deposited HfNxBy/n−/n+ diodes, determined from room temperature current-voltage characteristics, is 0.887 eV. This is lower than those of SBDs fabricated using other metals such as Au, where Φb is 1.79 eV. The HfNxBy/n−/n+ diodes studied have a much higher on-resistance Ron of around 38.24 mΩ-cm2, which is about four times that of Au/n−/n+ diodes, due to the higher sheet resistance of the sputtered HfNxBy electrode layer. The barrier height Φb and ideality factor η of the HfNxBy/n−/n+ diodes remain almost unchanged after 400 and 750 °C anneal in N2. This suggests excellent thermal and chemical stability of HfNxBy in contact with 4H-SiC. 相似文献
97.
Huseyin Kizil Gusung Kim Christoph Steinbrüchel Bin Zhao 《Journal of Electronic Materials》2001,30(4):345-348
The present status of work on diffussion barriers for copper in multilevel interconnects is surveyed briefly, with particular
emphasis on TiN and TaN, and silicon dioxide as the interlayer dielectric. New results are presented for these materials,
combining thermal annealing and bias temperature stress testing. With both stress methods, various testing conditions are
compared using capacitance-vs-voltage (C-V) and leakage current-vs-voltage (I-V) measurements to characterize the stressed
samples. From an evaluation of these data and a comparison with other testing approaches, conditions for a consistent testing
methodology of barrier reliability are outlined. 相似文献
98.
Dong-Soo Yoon Hong Koo Baik Sung-Man Lee Jae Sung Roh 《Journal of Electronic Materials》2001,30(5):493-502
The effects of the amount of RuO2 added in the Ta film on the electrical properties of a Ta-RuO2 diffusion barrier were investigated using n++-poly-Si substrate at a temperature range of 650–800°C. For the Ta layer prepared without RuO2 addition, Ta2O5 phase formed after annealing at 650°C by reaction between Ta and external oxygen, leading to a higher total resistance and
a non-linear I-V curve. Meanwhile, in the case of the Ta film being deposited with RuO2 incorporation, not only a lower total resistance and ohmic characteristics exhibited, but also the bottom electrode structure
was retained up to 800°C, attributing to the formation of a conductive RuO2 crystalline phase in the barrier film by reaction with the indiffused oxygen because of a Ta amorphous structure formed by
chemially strong Ta-O or Ta-Ru-O bonds and a large amount of conductive RuO2 added. Since a kinetic barrier for nucleation in formation of the crystalline Ta2O5 phase from an amorphous Ta(O) phase is much higher than that of crystalline RuO2 phase from nanocrystalline RuOx phase, the formation of the RuO2 phase by reaction between the indiffused oxygen and the RuOx nanocrystallites is kinetically more favorable than that of Ta2O5 phase. 相似文献
99.
The influence of high energy electron (HEE) irradiation from a Sr-90 radio-nuclide on n-type Ni/4H–SiC samples of doping density 7.1×1015 cm−3 has been investigated over the temperature range 40–300 K. Current–voltage (I–V), capacitance–voltage (C–V) and deep level transient spectroscopy (DLTS) were used to characterize the devices before and after irradiation at a fluence of 6×1014 electrons-cm−2. For both devices, the I–V characteristics were well described by thermionic emission (TE) in the temperature range 120–300 K, but deviated from TE theory at temperature below 120 K. The current flowing through the interface at a bias of 2.0 V from pure thermionic emission to thermionic field emission within the depletion region with the free carrier concentrations of the devices decreased from 7.8×1015 to 6.8×1015 cm−3 after HEE irradiation. The modified Richardson constants were determined from the Gaussian distribution of the barrier height across the contact and found to be 133 and 163 A cm−2 K−2 for as-deposited and irradiated diodes, respectively. Three new defects with energies 0.22, 0.40 and 0.71 eV appeared after HEE irradiation. Richardson constants were significantly less than the theoretical value which was ascribed to a small active device area. 相似文献
100.