多晶硅氧化镁的热稳定和快速的延迟时间分析-留学论文指导

Distinguished Paper: New Polycrystalline MgO for a Thermally Stableand Fast Delay Time in AC PDP优秀论文：在AC PDP中新建的多晶硅氧化镁的热稳定和快速的延迟时间分析

Abstract摘要

We have extensively studied polycrystalline MgO sources forachieving a thermally stable and fast delay time in AC PDP. 我们已广泛地研究了多晶硅的MgO源，这主要是用于实现在AC PDP的热稳定和快速的延迟时间的实验上。Thekey idea was to improve MgO film properties by doping p-type,equivalent, and n-type elements to the MgO matrix. Theirbehaviors in a gas discharge were tested. Most of them showedsevere discharge jitters. By doping Ca, Al, Si, and a particularn-type element, the discharge instability was greatly reduced, sothat the elements were studied in more details. We found thatdoping of the last element was highly effective in lowering thedelay time, improving the thermal stability, and lowering thefiring voltage. We proved that the improvement is largely due tothe electron emission enhanced by defects in MgO band gap andlattice distortion which is induced by dopants.我们已经验证了情况得到改善，主要的原因是由于引起掺杂剂的MgO的带隙性和晶格畸变的缺陷的电子发射增强的原因。http://www.ukassignment.org/lxslw/

Introduction介绍

R&D interest in plasma display panels (PDPs) is recently headingfor miniaturization of the gas discharge cells [1].R＆D主要研究的兴趣是在等离子显示面板（PDP）是最近的小型化的气体放电单元[1]的标题。 This trend isrelated to switching of the broadcasting signal format from SD-TVwith 480i to HD-TV with 1080i. To reduce the cell size is not aproblem at all. It is relatively easy within the framework ofnanotechnology. The performance, however, is definitely different.Until now, despite of many efforts to optimize the cell structure anddriving waveforms, results are not acceptable yet. This implies thatthe difficulty comes from limitations of existing materials. In otherwords, new materials are clearly required to overcome the obstacles.A PDP is well known as a display device converting electricalsignals to images [2]. Various errors appear in the conversion. Mostof them are due to unstable gas discharges. This is a general featureof gas discharge that is formed through complex electrical processes,like interactions between an MgO film, gases and electrons. So thecontrol is very intricate but entirely needed to reproduce an imageclearly. Discharge instability may occur due to various causes.Probable causes are deviation in cell structure, gas purity, MgOquality, and phosphor quality. Among them, MgO quality has beenrecently recognized as the dominant cause, especially serious forminiaturized cells.其中，氧化镁的质量已经被确认作为其主导地位的因素，尤其是在小型化细胞之中，更加重要。

An MgO film used in PDPs belongs to a wide band-gap oxide (Eg~7.8eV in single crystal) with a low electron affinity (χ ~ 0.8eV).The sum of Egand χ is closely related to the secondary electronemission coefficient γ [3], and if the sum is smaller, then thecoefficient γ rises, reducing the discharge instability. Doping of foreign atoms to the MgO matrix is a method for decreasing Egand χ.MgO single crystals are grown at an extremely high temperature(~2800°C), so that doping is beyond control due to the very lowsolubility and stability of most doping elements. Consequently, wehave used MgO poly-crystals as the doping matrix. This matrix’ssintering temperature is relatively low (~1650 °C), which enables todope various elements to MgO with less troubles with the solubilityand stability.

Experimental实验

Our experiments are divided into three groups: 我们的实验中被分为三组：to study dopedMgO basically;掺杂氧化镁的基本研究; to do panel pilots; to analyze pellets and films ofdoped MgO. 做面板实验员;分析掺氧化镁颗粒和薄膜。We prepared MgO pellet sources for e-beam deposition.Doping of different elements to MgO was done during themanufacturing process of MgO pellets. Doping elements were sortedout according to their doping type: Li and Cu for p-type atoms; Baand Ca for equivalent atoms; Al, Ga, Ge, Si, Ti, and a particularelement for n-type atoms. Usual MgO single crystal sources containunintentionally doped impurities such as Ca, Al, Fe, and Si, with aconcentration of about 200 ppm, 80 ppm, 70 ppm, and 100 ppm,respectively. Unlike single crystals, polycrystals can be purifiedbelow 10 ppm for Ca, Al, Fe, and Si, respectively. Usual polysources contain Zr of about 100 ppm, which may be introduced bythe zirconia ball milling of an organic vehicle and MgO powder.Pure and un-doped MgO pellets are different from each other. Forpure MgO, each of Ca, Al, Fe, Si, and Zr is below 10 ppm, and forun-doped MgO, their contents are <1 ppm, 50 ppm, 25 ppm, 50 ppm,and 100 ppm, respectively. MgO pellets of high purity, as well asun-doped and doped MgO pellets were used to make MgO filmsusing an e-beam deposition apparatus. For the basic study, thedeposition was done at oxygen flow rate of 50 sccm and depositionrate of 60 ?/s. The base pressure, the working pressure, and thesubstrate temperature were fixed to 3x10-5Torr, 6x10-4Torr, and 250°C, respectively. The working pressure was kept with Ar. Thethickness of MgO films was 700 nm. Films were analyzed by using adischarge cell with an opposed arrangement of two identical MgOfilms. Our previous article [4] described it in more details.我们以前的文章描述了它在更多方面上的细节。

Two different panel pilots were performed in order to compareresults of the test cells with real panels.为了得到一个比较的测试结果， 飞行员进行了两种不同的面板，细胞的测试方法。The goal of the first pilot wasto fabricate and characterize a widescreen (16:9) 480-line format: 42”PDP, 852 x 480p, with single scan operation. All manufacturingprocesses were performed in a small-scale pilot line having a batch-type, e-beam apparatus. The second pilot was done for anextended graphics adaptor (XGA) format: 42” PDP, 1024 x 768p,with single scan operation in a mass production line. This line usesan in-line plasma evaporation process.

In order to give a logical explanation to highly improved dischargeproperties, surfaces of MgO pellets and films were analyzed. Thetype, amount, and stability of doping species were checked out byusing inductively coupled plasma-atomic emission spectroscopy(ICP-AES) and secondary ion mass spectroscopy (SIMS). Changesin the electronic structure induced by defects in the band gap of MgOfilms were examined by using cathodoluminescence (CL).

通过使用阴极发光（CL），；来对引起的缺陷的氧化镁薄膜的带隙的电子结构的变化进行了检查。