Enhanced electron emission from phosphorus-doped diamond-cladsilicon field emitter arrays

Undoped and phosphorus (P)-doped diamond-clad Si field emitter arrays have been successfully fabricated using microwave plasma chemical vapor deposition (MPCVD) technology. The electron emission from the blunt diamond-clad microtips are much higher than those for the pure Si tips with sharp curvature due to a lower work function. Furthermore, the characteristics of emission current against applied voltage for the P-doped diamond-clad tips show superior emission at lower field to the undoped ones. After the examination of Auger electron spectroscopy (AES) and electrical characteristics of as-grown diamond, such a significant enhancement of the electron emission from the P-doped diamond-clad tips is attributed to a higher electron conductivity and defect densities     

金刚石薄膜的形成及其场发射特性研究

研究了金刚石聚晶碳膜的生长过程,以及不同生长阶段碳膜的场发射性能。通过磁控溅射法在陶瓷上镀一层金属钛作为制备碳膜的衬底,将衬底放入微波等离子体化学气相沉积腔中,经过不同的沉积时间制备出一系列的碳膜。利用SEM、Raman光谱仪、X射线衍射仪等仪器,对碳膜进行了形貌与成分分析,最后利用二极结构场发射装置,测试了碳膜的场发射性能。着重讨论了金刚石聚晶碳膜生长过程中的变化,并且对金刚石聚晶碳膜的场发射机理进行了深入研究。     

两种微米金刚石聚晶颗粒薄膜的制备与场发射研究

采用微波等离子体化学气相沉积,在不同的沉积条件下得到两种微米金刚石颗粒薄膜,通过拉曼光谱仪和X射线仪分析了两种薄膜的成分,用扫描电子显微镜分析了两种薄膜的表面形貌,用二级结构的场发射装置研究了薄膜的场发射性能,最终分析并讨论了场发射性能优异的微米金刚石薄膜的特征。     

Modeling of carrier mobility against carrier concentration in arsenic-, phosphorus-, and boron-doped silicon

New carrier mobility data for both arsenic- and boron-doped silicon are presented in the high doping range. The data definitely show that the electron mobility in As-doped silicon is significantly lower than in P-doped silicon for carrier concentrations higher than 10¹⁹cm^-3. By integrating these data with those previously published, empirical relationships able to model the carrier mobility against carrier concentration in the whole experimental range examined to date (about eight decades in concentration) for As-, P-, and B-doped silicon are derived. Different parameters in the expression for the n-type dopants provide differentiation between the electron mobility in As-and in P-doped silicon. Finally, it is shown that these new expressions, once implemented in the SUPREM II process simulator, lead to reduced errors in the simulation of the sheet resistance values.     

金刚石薄膜场发射显示器

简要介绍了一般ＦＥＤ（场发射显示器）的工作原理,研究了非晶金刚石薄膜低场发射特点,讨论了金刚石薄膜制做场发射器的可行性;指出利用金刚石薄膜和阳极选择的方法可对Ｓｐｉｎｄｔ ＦＥＤ进行改进,从而使平面ＦＥＤ更容易实现。     

应用于FED的金刚石薄膜的光学和结构分析

本文比较研究了不同晶粒大小和结构的金刚石薄膜的场发射性质,这些金刚石薄膜通过热丝辅助化学气相沉积法(HFCVD)获得.研究结果表明纳米尺寸效应对金刚石薄膜的场发射性能有非常重要的影响,通过比较不同晶粒尺寸的金刚石薄膜发现纳米金刚石薄膜相对于大晶粒金刚石薄膜(比如微米级的金刚石薄膜)有更好的场发射性能.从拉曼光谱得到,含有一定量非金刚石相的金刚石薄膜有更好的场发射能力和更低的开启电场(E0).另外,具有(111)定向的金刚石薄膜比起其他结构的金刚石薄膜,它的电子发射能力更强.     

Properties of phosphorus-doped (Zn,Mg)O thin films and device structures

The properties of phosphorus-doped (Zn,Mg)O polycrystalline and epitaxial thin films are described. The as-deposited (Zn,Mg)O:P films are n type with high electron carrier density. High resistivity is induced in the films with moderate temperature annealing, which is consistent with suppression of the donor state and activation of the deep acceptor. The resistivity of the as-deposited and annealed film is an order of magnitude higher than similar samples with no Mg, consistent with a shift in the conduction band edge relative to the defect-related donor state. The capacitance-voltage characteristics of annealed metal/insulator/P-doped (Zn,Mg)O structures in which the (Zn,Mg)O is polycrystalline exhibit p-type polarity. In addition, multiple polycrystalline devices comprising n-type ZnO/P-doped (Zn,Mg)O thin-film junctions display asymmetric I–V characteristics that are consistent with the formation of a p-n junction at the interface, although the ideality factor is anomalously high.     

Characterization of deep defects in boron-doped CVD diamond films using transient photocapacitance method

We have developed a highly-sensitive transient photocapacitance measurement (TPM) system for deep defects in wide bandgap materials, and applied it to characterize the boron-doped diamond films grown on a high-pressure/high-temperature-synthesized Ib diamond substrate using high-power-density microwave-plasma chemical vapor deposition method. The developed TPM system has both a low detection limit of less than 0.5 fF for changes in the photocapacitance and a low measurement temperature drift of less than 0.03 K in 12 h. By using the TPM system, we have successfully found an acceptor-type defect around 1.2 eV above the valence-band maximum for the B-doped diamond film with a considerably high crystalline quality that had some strong exciton emission peaks in the cathodoluminescence spectra taken at ≈80 K. The photoionization cross section and the defect density estimated for the observed defect were 3.1×10^–15 cm² and 2.8×10¹⁶ cm⁻³, respectively.     

Bipolar transistor fabrication using selective epitaxial growth ofP- and B-doped layers in gas-source Si molecular beam epitaxy

Si n-p-n bipolar transistor fabrication using selective epitaxial growth in disilane gas-source Si molecular beam epitaxy (Si-MBE) is discussed. Selective growth of B-doped and P-doped Si was used for the base- and emitter-layer formation, respectively. The growth temperature was 600°C. No ion-implantation process was used. The base ohmic contact was formed using Al selective chemical vapor deposition. The fabricated transistor showed normal emitter-base and base-collector I-V characteristics. The common-emitter characteristics revealed a maximum current gain of 30     

Spatial correlation of electron field emission sites withnon-diamond carbon content in CVD diamond

Field-induced electron emission is obtained from 15 mm diameter CVD polycrystalline diamond films deposited on silicon wafers from a microwave discharge. These films were grown such that the percentage of non-diamond carbon is highest at the edge of the film. It was found that the majority of the emission sites also occured at the edge of the film     

脉冲激光沉积非晶碳-聚酰亚胺复合薄膜的场致电子发射研究

利用脉冲激光沉积技术制备出非晶碳-聚酰亚胺复合薄膜,并观察到其场发射阈值场强(4V/μm)比类金刚石薄膜(>12V/μm)有较大的降低,最大发射电流密度为1.2mA/cm~2.利用透明导电薄膜阳极技术可观察电子在薄膜阴极表面的发射位置.并对该复合薄膜的场电子发射机理进行了初步探讨.实验表明该复合薄膜有可能作为一种新型的场发射冷阴极材料.在平面显示器件中得到应用.     

金刚石基底上制备(002)AlN薄膜的研究

首先采用微波等离子体化学气相沉积(MPCVD)方法,在O2/H2/CH4混合气体气氛下利用大功率微波在(100)Si片上生长出了异质外延金刚石膜,X-射线衍射(XRD)、拉曼光谱和场发射扫描电子显微镜(FESEM)对薄膜的表征分析结果表明,制备的金刚石膜具有很高的金刚石相纯度,且晶粒排列紧密;继而采用射频磁控反应溅射法,在抛光的金刚石基底上成功制备了高C轴择优取向的氮化铝(AlN)薄膜,研究了不同的溅射气压、靶基距对AlN薄膜制备的影响,XRD检测结果表明,溅射气压低,靶基距短,有利于AlN(002)面择优取向,相反则更有利于AlN薄膜的(103)面和(102)面择优取向;研究了AlN薄膜在以N终止的金刚石基底和纯净金刚石基底两种表面状态上的生长机制,结果发现,以N终止的金刚石基底非常有利于AlN(002)面择优取向生长;从Al-N化学键的形成以及溅射粒子平均自由程的角度,探讨了其对AlN薄膜择优取向的影响。     

Field-dependence of the area-density of 'cold' electron emission sites on broad-area CVD diamond films

A high area density of field-induced electron emission sites has been observed on broad-area (12 mm in diameter) CVD diamond films deposited on molybdenum substrates. Furthermore, it was found that the density increased with the electric field applied to the surface of the films. These findings indicate that the CVD diamond film has to be seen as a potentially favoured candidate among electronic materials for the development of new types of cold cathode electron source.<>     

CVD金刚石（膜）制备技术及应用进展

化学气相沉积（CVD）方法是金刚石（膜）制备的主流技术,经过多年的发展,已从最初的微米金刚石膜发展到纳米金刚石膜,至目前高质量的单晶金刚石,应用领域不断扩展。除了工业和民用领域外,纳米金刚石膜在MEMS／NEMs、生物医学的应用进展引起业界关注,其中大尺寸单晶金刚石的制备是推动这些应用的关键。本文分析了MPCVD金刚石成膜特点,讨论了现阶段CVD金刚石膜商业化推广应用的制约因素,展望了今后金刚石膜的发展前景。     

微米金刚石聚晶薄膜场发射点的研究

采用微波等离子化学气相沉积方法,以甲烷和氢气为反应气体,在镀有金属钛的陶瓷衬底上,制备了微米金刚石聚晶薄膜.利用扫描电镜、拉曼光谱、X射线光电子能谱对薄膜的化学组成、微观结构和表面形貌进行了表征.用二级结构的场发射仪和扫描隧道显微镜研究了薄膜的场发射性能,结果表明微米金刚石聚晶薄膜发射点主要来源于聚晶颗粒.进一步研究了单个聚晶颗粒表面不同区域的发射性能,发现多种因素对场发射的性能有影响.     

Poly-diamond gated field-emitter display cells

A microchip containing gated field-emitter display (FED) cells is designed and fabricated using vapor-deposited p-type polycrystalline diamond films and employing an integrated circuit (IC)-compatible diamond film technology on oxidized 4-in Si wafers. Current-voltage (I-V) data, measured in a diode configuration at 10^-6 torr, show Fowler-Nordheim (F-N) field emission behavior. A 1×4 pixel diamond gated display cell is demonstrated for the first time using phosphor-coated glass as an anode     

用于场发射阴极的磁控溅射金刚石薄膜的研究

用激光拉曼谱和原子力显微镜等现状分析手段研究了磁控溅射石墨靶制备的薄膜的结构和特性。结果表明：薄膜由金刚石相和石墨相组成，它们的相对含量取决于制备工艺参数，特别是沉积时的基体温度的影响尤为明显。薄膜表面呈现为密度很高的微尖锥，这为制造大面积场发射平板显示器的阴极提供了广阔的前景。     

C-H体系CVD金刚石薄膜取向生长的热力学分析

化学气相淀积金刚石薄膜过程中 ,CH3 和C2 H2 是金刚石生长的主要前驱基团。C2 H2 与CH3 浓度比 ( [C2 H2 ]/[CH3 ])的变化将影响金刚石薄膜的生长取向。用非平衡热力学耦合模型计算了C H体系CVD金刚石薄膜生长过程中C2 H2 浓度和CH3浓度随淀积条件的变化 ,并进一步获得了 [C2 H2 ]/[CH3 ]随衬底温度和CH4浓度的变化关系 ,从理论上探讨了金刚石薄膜 ( 1 1 1 )面和 ( 1 0 0 )面取向生长与淀积条件的关系。在衬底温度和CH4浓度由低到高的变化过程中 ,[C2 H2 ]/[CH3 ]逐渐升高 ,导致金刚石薄膜的形貌从 ( 1 1 1 )晶面转为 ( 1 0 0 )晶面。     

硫掺杂纳米金刚石薄膜的图形化生长

利用电子增强热丝化学气相沉积(EACVD)技术,以CH4/H2/H2S/Ar为工作气体,SiO2/Si为衬底,制备了硫掺杂金刚石薄膜。研究了利用光刻技术实现薄膜的图形化生长。结果表明:以SiO2作掩模的光刻技术能够使得硫掺杂金刚石薄膜在光滑SiO2/Si基片上很好地图形化生长。Hall效应检测表明硫掺杂金刚石薄膜为n型,给出了n型金刚石/p-Si异质结的反向I-V特性曲线。     

超纳米金刚石薄膜场发射特性的研究

超纳米金刚石(UNCD)是一种全新的纳米材料，具有许多独特性能。介绍了Si微尖和微尖阵列阴极沉积超纳米金刚石薄膜的工艺及其场发射特性。研究发现，适当的成核工艺和微波等离子体化学气相沉积工艺可在Si微尖上沉积一层光滑敷形的金刚石薄膜；沉积后阴极的电压-电流特性、发射电流的稳定性以及工作在氧气环境下的发射特性都获得明显提高。讨论了超纳米晶金刚石薄膜阴极的发射机理。