激光分子束外延法制备AlN/Si异质结的电学性质

采用激光分子束外延法在Si(111)衬底上制备出沿c轴取向的AlN薄膜,在此基础上制备了Au/AlN/Si金属-绝缘体-半导体(MIS)结构。研究了结构的电流传输机制、AlN/Si界面处的界面态密度值及分布情况。结果表明:AlN/Si异质结具有很好的整流特性,电流传输符合空间电荷限制传输机制,理想因子为2.88;结构的界面态密度约为1.1×10~(12) eV~(-1)·cm~(-2),主要分布在距离Si衬底价带顶0.26eV附近,由生长过程中引入的O杂质、N空位/N替代和Si原子代替N原子形成的Al-Si键组成。     

Space charge limited conduction in CdSe thin films

The current (I)-voltage (V) characteristics of thermally evaporated CdSe thin films having thickness in the range 850–3000 Å and deposited within the substrate temperature of 303–573 K show nearly linear dependence at low voltage and afterwards a non-linear behaviour at higher voltage range. A detailed study ofI-V curves in dark and under illumination clearly reveals the mechanism as ohmic at low voltage and that of trap limited space charge limited conduction (SCLC) at higher voltage. The transition voltage (V_t) from ohmic to SCLC is found to be quite independent of ambient temperature as well as intensity of illumination. SCLC is explained on the basis of the exponential trap distribution in CdSe films. Trap depths estimated from the lnI vs 10³/T plots are found to be within 0.60-0.37 eV. Using the relevant SCLC theory, the carrier concentration, n₀, total trap concentration, N_t, and the ratio of free charge to trapped charge, θ, have been calculated and correlated with ambient temperature and intensity of illumination.     

激光分子束外延法制备AlN/Si异质结的电学性质

采用激光分子束外延法在Si(111)衬底上制备出沿c轴取向的AlN薄膜，在此基础上制备了Au/AlN/Si 金属 绝缘体 半导体(MIS)结构。研究了结构的电流传输机制、AlN/Si界面处的界面态密度值及分布情况。结果表明：AlN/Si异质结具有很好的整流特性，电流传输符合空间电荷限制传输机制，理想因子为2.88；结构的界面态密度约为1.1×1012 eV-1·cm-2，主要分布在距离Si衬底价带顶0.26 eV附近，由生长过程中引入的O杂质、N空位/N替代和Si原子代替N原子形成的Al-Si键组成。     

Optimizing endurance performance of Ga2O3 random resistive access memories by altering oxygen vacancy content

In this work, we propose an effective way to improve the endurance performance of Ga₂O₃ resistive random access memories by doping ZnO. Excellent bipolar resistive switching behaviors have been observed in atomic-layer-deposited ZnO-doped Ga₂O₃ RRAMs, which exhibit large memory windows over 10³ and retention time up to 10⁴. Bipolar resistive switching behaviors can be explained by the formation or rupture of conductive filaments composed of Ag atoms and oxygen vacancies. Current – voltage curves suggest Ohmic conductance of the low resistance states, while the conductive mechanism of the high resistance states corresponds to the trap-assisted space charge limited conduction. Furthermore, the reason why the endurance performance of ZnO-doped Ga₂O₃ RRAMs is better than pure Ga₂O₃ RRAMs is analyzed.     

Thickness effect on the bipolar switching mechanism for nonvolatile resistive memory devices based on CeO2 thin films

Impact of switching layer thickness on the bipolar resistive memory performance, stability and uniformity has been investigated in Ti/CeO₂/Pt devices. XRD and FTIR analyses demonstrate polycrystalline nature of CeO₂ films and the formation of a TiO interface layer. The bipolar switching characteristics like HRS and LRS dispersion are found to be dependent on the thickness of CeO₂ layer. As it is noted that forming as well as SET voltages gradually increase with increasing CeO₂ layer thickness however RESET voltages are slightly affected. Oxygen gettering ability of Ti causes the formation of TiO layer, which not only extracts oxygen ions from the ceria film but also acts as ion reservoir, hence plays a key role in stable functioning of the memory devices. Current transport behavior is based upon Ohmic and interface modified space charge limited conduction. Based on unique distribution characteristics of oxygen vacancies in CeO₂ films, a possible mechanism of resistive switching in CeO₂ RRAM devices has been discussed.     

Investigation of electrical conductivity in Schottky-barrier devices based on nickel phthalocyanine thin films

Evaporated multilayer sandwich structure of Au/NiPc/Al was fabricated by thermal evaporation technique. The electrical conductivity of Au/NiPc/Al device has been measured both as prepared and after annealing at 623 K for 2 h. Under forward bias conditions, ohmic and SCLC conductions were identified at low and higher voltages respectively. After annealing, a strong rectifying effect was observed. The potential barrier height and the depletion region width for annealed sample were calculated as 0.96 eV and 70 nm, respectively. Hole and trap parameters for as prepared and after annealing devices, also, were evaluated.     

量子点发光二极管中载流子注入机理的研究

针对量子点(QDs)发光二极管(QLED)中载流子注 入不平衡的问题,对载流子的注入机理进行了研 究。在隧穿注入和空间电荷限制电流(SCLC)模型的基础上,仿真分析了空穴和电子在QDs 层的注入情况,制备 了QLED的样品。CdSe/CdS作为QDs层,PEDOT:PSS作为空穴注入层(HIL),TPD作为 空穴传输层(HTL),Alq₃作为电子传输层(ETL)。优选的QDs层厚为25nm时,确定了TPD和Alq₃的理论最优厚分别为48nm。研究发现, 当驱动电压低于6.5V时,隧穿注入电流在载流子的传输过 程中起主导作用;高于6.5V时,SCLC在载流子的传输过程中起主导 作用。实验结果表明,当 Alq₃厚为20nm时,器件发出QDs的红光,随着Alq₃厚度的增加, 器件开始出现绿光,实验结果与仿 真结果基本吻合。研究结果对QLED的制备具有理论借鉴意义。     

HfOxNy栅介质薄膜的电学特性

用直流溅射方法制备了HfOxNy薄膜，对其电学特性和导电机理进行了研究. 实验结果表明,引入铪缓冲层并在氮气中退火有助于改善电学性能. 研究了薄膜在电场下的漏电机理，发现在负向低电场下I-V特性遵从欧姆规律，在中强电场下导电机制遵从空间电荷限制电流理论.     

Direct current electrical characterization of plasma polymerized pyrrole-N,N,3,5 tetramethylaniline bilayer thin films

The direct current conduction mechanism in plasma polymerized pyrrole-N,N,3,5 tetramethylaniline (PPPy-PPTMA) bilayer thin films has been discussed in this article. A parallel plate capacitively coupled glow discharge reactor was used to deposit PPPy, PPTMA, and PPPy-PPTMA thin films at room temperature onto glass substrates. The Fourier Transform Infrared analyses showed that the PPPy-PPTMA bilayer thin films contained the structural characteristics of both the PPPy and PPTMA. The current density-voltage characteristics of PPPy-PPTMA bilayer thin films of different deposition time-ratios indicated an increase in electrical conductivity as the proportion of PPTMA was increased in the bilayer films. It is also observed that the conductivity of the bilayer thin film is reduced compared with its component thin films. It is seen that in the low voltage region the current conduction obeys Ohm's law, while the charge transport phenomenon appears to be the space charge limited conduction in the higher voltage region. The mobility of the charges, the free charge carrier density, and the permittivity of the PPPy, PPTMA and PPPy-PPTMA bilayer thin films have been calculated. The permittivity for PPPy, PPTMA and PPPy-PPTMA bilayer thin films were found to be 1.07 × 10⁻¹⁰, 2.2 × 10⁻¹¹, and 1.26 × 10⁻¹⁰ C² N⁻¹ m⁻², respectively; the free charge carrier density were (3.56 ± 0.01) × 10²², 2 × 10²¹ and (5.19 ± 0.02) × 10²² m⁻³ respectively; and the mobility of the charges were found to be (4.4 ± 0.01) × 10⁻¹⁹, 1.3 × 10⁻¹³ and (2.1 ± 0.01) × 10⁻¹⁹ m² V⁻¹ s⁻¹ respectively. PACS: 72.80.Le, 73.21.Ac, 73.40.Rw, 73.50.Gr, 73.61.Ph. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

抗-ProGRP单克隆抗体的筛选及其在小细胞肺癌鉴别诊断中的意义

目的 筛选与小细胞肺癌（SCLC）组织胃泌素释放肽前体（ProGRP）抗原具有高亲和力的抗．ProGRP单克隆抗体,探讨抗．ProGRP单克隆抗体在小细胞肺癌临床鉴别诊断中的意义。方法运用免疫组织化学方法筛选高亲和力抗．ProGRP单克隆抗体;利用筛选出的高亲和力抗体分别与SCLC、NscLc、肺良性肿瘤组织切片进行抗原抗体反应,检测ProGRP抗原的阳性表达率。结果抗-ProGRP单克隆抗体V-B3与SCLc组织ProGRP抗原的亲和力最高。21例SCLC组织,阳性表达率为90．5％;28例NSCLC组织,阳性表达率为28．6％;23例肺良性疾病组织,阳性表达率为8．7％。结论应用免疫组织化学方法检测SCAC组织中ProGRP抗原的表达,可以对SCLC进行临床鉴别诊断。