Design and Experimental Study of Deposition Temperature Control System in Ultra-High Vacuum

2012 ◽  
Vol 571 ◽  
pp. 564-568
Author(s):  
Zhi Dan Yan ◽  
Li Dong Sun ◽  
Chun Guang Hu ◽  
Xiao Tang Hu ◽  
Peter Zeppenfeld
Keyword(s):  
Control System ◽  
Temperature Control ◽  
Deposition Temperature ◽  
Film Growth ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Temperature Control System ◽  
Growth Morphology ◽  
Precise Control ◽  
Key Factor

Deposition temperature is a key factor influencing the growth morphology of thin-films, aiming at this phenomenon, a precise control system of deposition temperature in ultra-high vacuum is developed in the paper. It can realize accurate temperature control in a range of 150K to 450K during experiment by combination of resistance heating up and liquid helium cooling down strategies, which is benefit to further understand the temperature-depended mechanism of organic molecule thin-film growth. Besides, it is experimentally studied that the growth morphology of p-6p molecules on a mica substrate is closely related to the substrate deposition temperature, indicating that the length of p-6p nano-fibers is proportional to the deposition temperature, while their distribution density is inversely proportional to the temperature.

ARM-Based Resistance Furnace Neural Network Temperature Control System Design

2013 ◽  
Vol 319 ◽  
pp. 562-566 ◽  
Author(s):  
Hong Fang ◽  
Hong Lian Li
Keyword(s):  
Neural Network ◽  
Control System ◽  
Temperature Control ◽  
Pid Control ◽  
Control Algorithm ◽  
Temperature Control System ◽  
Resistance Furnace ◽  
Digital Conversion ◽  
Precise Control ◽  
Single Neural Network

to promote the measuring and controlling precisions of temperature control system, in this paper, a temperature detecting circuit is made up of thermocouple and digital conversion chip MAX6675 with ARM chip at its core. The PID control algorithm of single neural network is also brought up herein and adopted in simulating the temperature control system of resistance furnace. The result shows that PID control algorithm of single neural network can achieve better controlling effects than the traditional one and realize precise control over temperature.

Direct STEM ADF imaging of gold on silicon (111)

1989 ◽  
Vol 47 ◽  
pp. 472-473
Author(s):  
P. Xu ◽  
E. J. Kirkland ◽  
J. Silcox
Keyword(s):  
Film Growth ◽  
Heavy Atom ◽  
High Vacuum ◽  
Dark Field ◽  
Thin Metal Film ◽  
Base Pressure ◽  
Ultra High Vacuum ◽  
Specimen Preparation ◽  
Dark Field Imaging ◽  
Wide Range

Many studies of thin metal film growth and the formation of metal-semiconductor contacts have been performed using a wide range of experimental methods. STEM annular dark field imaging could be an important complement since it may allow direct imaging of a single heavy atom on a thin silicon substrate. This would enable studies of the local atomic arrangements and defects in the initial stage of metal silicide formation.Preliminary experiments were performed in an ultra-high vacuum VG HB501A STEM with a base pressure of 1 × 10-10 mbar. An antechamber directly attached to the microscope for specimen preparation has a base pressure of 2×l0-10 mbar. A thin single crystal membrane was fabricated by anodic etching and subsequent reactive etching. The specimen was cleaned by the Shiraki method and had a very thin oxide layer left on the surface. 5 Å of gold was deposited on the specimen at room temperature from a tungsten filament coil monitored by a quartz crystal monitor.

Modifications of a JEOL 2000EX TEM for insSitu surface studies

1993 ◽  
Vol 51 ◽  
pp. 640-641
Author(s):  
Michael T. Marshall ◽  
Xianghong Tong ◽  
J. Murray Gibson
Keyword(s):  
Electron Diffraction ◽  
Surface Science ◽  
Film Growth ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Transmission Electron ◽  
Fundamental Insight

We have modified a JEOL 2000EX Transmission Electron Microscope (TEM) to allow in-situ ultra-high vacuum (UHV) surface science experiments as well as transmission electron diffraction and imaging. Our goal is to support research in the areas of in-situ film growth, oxidation, and etching on semiconducter surfaces and, hence, gain fundamental insight of the structural components involved with these processes. The large volume chamber needed for such experiments limits the resolution to about 30 Å, primarily due to electron optics. Figure 1 shows the standard JEOL 2000EX TEM. The UHV chamber in figure 2 replaces the specimen area of the TEM, as shown in figure 3. The chamber is outfitted with Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), Residual Gas Analyzer (RGA), gas dosing, and evaporation sources. Reflection Electron Microscopy (REM) is also possible. This instrument is referred to as SHEBA (Surface High-energy Electron Beam Apparatus).The UHV chamber measures 800 mm in diameter and 400 mm in height. JEOL provided adapter flanges for the column.

Studies of Ge/Si(100) and Observation of Atomic Steps on Si(100) using Biassed Secondary Electron Imaging in a UHV STEM

1990 ◽  
Vol 48 (1) ◽  
pp. 308-309
Author(s):  
Mohan Krishnamurthy ◽  
Jeff S. Drucker ◽  
John A. Venablest
Keyword(s):  
Secondary Electron ◽  
Critical Thickness ◽  
Surface Defects ◽  
Film Growth ◽  
Growth Parameters ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Surface Steps ◽  
Epitaxial Crystal Growth ◽  
Electron Imaging

Secondary Electron Imaging (SEI) has become a useful mode of studying surfaces in SEM[1] and STEM[2,3] instruments. Samples have been biassed (b-SEI) to provide increased sensitivity to topographic and thin film deposits in ultra high vacuum (UHV)-SEM[1,4]; but this has not generally been done in previous STEM studies. The recently developed UHV-STEM ( codenamed MIDAS) at ASU has efficient collection of secondary electrons using a 'parallelizer' and full sample preparation system[5]. Here we report in-situ deposition and annealing studies on the Ge/Si(100) epitaxial system, and the observation of surface steps on vicinal Si(100) using b-SEI under UHV conditions in MIDAS.Epitaxial crystal growth has previously been studied using SEM and SAM based experiments [4]. The influence of surface defects such as steps on epitaxial growth requires study with high spatial resolution, which we report for the Ge/Si(100) system. Ge grows on Si(100) in the Stranski-Krastonov growth mode wherein it forms pseudomorphic layers for the first 3-4 ML (critical thickness) and beyond which it clusters into islands[6]. In the present experiment, Ge was deposited onto clean Si(100) substrates misoriented 1° and 5° toward <110>. This was done using a mini MBE Knudsen cell at base pressure ~ 5×10-11 mbar and at typical rates of 0.1ML/min (1ML =0.14nm). Depositions just above the critical thickness were done for substrates kept at room temperature, 375°C and 525°C. The R T deposits were annealed at 375°C and 525°C for various times. Detailed studies were done of the initial stages of clustering into very fine (∼1nm) Ge islands and their subsequent coarsening and facetting with longer anneals. From the particle size distributions as a function of time and temperature, useful film growth parameters have been obtained. Fig. 1 shows a b-SE image of Ge island size distribution for a R T deposit and anneal at 525°C. Fig.2(a) shows the distribution for a deposition at 375°C and Fig.2(b) shows at a higher magnification a large facetted island of Ge. Fig.3 shows a distribution of very fine islands from a 525°C deposition. A strong contrast is obtained from these islands which are at most a few ML thick and mottled structure can be seen in the background between the islands, especially in Fig.2(a) and Fig.3.

Temperature Control System for Transformer Three-Phase 50 Hz 2500 kVA

2017 ◽  
Vol 3 (2) ◽  
pp. 88
Author(s):  
Suci Rahmatia ◽  
Marsah Zaysi Makhudzia
Keyword(s):  
Optimal Control ◽  
Control System ◽  
Heat Loss ◽  
Temperature Control ◽  
Electrical Energy ◽  
Temperature Control System ◽  
Iron Core ◽  
Electrical Device ◽  
Optimal Control System ◽  
Three Phase

<p><em>Abstrak <strong>- </strong></em><strong>Transformator adalah peralatan listrik yang sangat vital dalam proses pembangkitan maupun transmisi energi listrik karena transformator dapat menaikkan atau menurunkan tegangan. Pada proses menaikkan dan menurunkan tegangan biasanya sering timbul panas akibat rugi – rugi tembaga pada inti besi dan kumparannya sehingga pada kondisi overload akan menimbulkan pemanasan yang berlebih dan dapat mempengaruhi kinerja transformator. Oleh karena itu dibuat sistem kontrol temperatur pada transformer yang dapat mengontrol temperatur di dalam transformator saat bekerja pada kondisi overload, sehigga transformatornya tidak terbakar. Dial thermometer digunakan sebagai alat yang mengontrol temperatur transformator pada sistem kontrol temperatur. Agar mendapatkan sistem kontrol yang optimal, maka setting temperatur pada dial thermometer di sesuaikan dengan temperatur maksimal tranformator dapat bekerja. Sehingga pada saat temperatur tertentu dial thermometer dapat memberikan sinyal untuk membunyikan alarm dan mengaktifkan kontrol kipas sehingga kipas dapat bekerja menurunkan temperatur transformator.<em></em></strong></p><p><strong><em> </em></strong></p><p><strong><em>Kata kunci - </em></strong><em>transformator, rugi – rugi tembaga, temperatur, sistem kontrol, dial thermometer<strong>.</strong></em></p><p><strong><em> </em></strong></p><p><em>Abstract <strong>- </strong></em><strong>A transformer is an electrical device that is vital in the generation and transmission of electrical energy because the transformer can raise (stepping up) or lower (stepping down) the voltage. In the process of raising and lowering the voltage is usually often caused heat loss of copper in iron core and coil so that the overload condition will cause excessive warming and can affect the performance of the transformer. Therefore, a temperature control system on the transformer can control the temperature inside the transformer while working under overload conditions, so the transformer is not burned. Dial thermometer is used as a device that controls the temperature of the transformer in the temperature control system. In order to obtain an optimal control system, the temperature setting on the dial thermometer adjusted to the maximum transformer temperature can work. So that when a certain temperature dial thermometer can provide a signal to sound the alarm and activate the fan control so that the fan can work down the transformer temperature.</strong></p><p><strong> </strong></p><p><strong><em>Keywords -  </em></strong><em>transformator, loss of copper, themperature, control system, dial thermometer<strong></strong></em></p>

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