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Al/CuPc/Cu Schottky Diode Gas Sensing Characteristics

Posted on:2012-10-28Degree:MasterType:Thesis
Country:ChinaCandidate:X L LiuFull Text:PDF
GTID:2218330368977630Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
In electronic devices field, there has been considerable interest in the study of organic substances such as phthalocyanines in thin film form for use as the active layer in gas sensor devices. This is because the electronic properties of metal phthalocyanine (MPc) thin films are known to be affected by the presence of a foreign gas. The measure of conductivity change in the presence of the gas being detected is one of the most commonly used parameters in sensor devices using MPc thin films. Various MPc thin films have been investigated for gas sensing properties. In particular, vacuum-deposited MPc thin films were intensively studied for their high sensitivity to nitrogen dioxide (NO2) gas.In this paper, magnetron sputtering and vacuum deposition technology were used to prepare two kinds of Schottky diodes whose organic layer are different. Then the appropriate experimental program was designed to measure and analyze the sensitive characteristics. The devices that were fabricated on the glass organic used semiconductor materials copper phthalocyanine (CuPc) as the sensitive layer , and the structure consists of Cu/CuPc/Al layers. The Cu/CuPc that form ohmic contact act as anode of the devices, CuPc/Al that form Schottky contact act as the cathode. The electrodes at both ends of the devices were fabricated by DC magnetron sputtering. The organic semiconductor copper phthalocyanine (CuPc) in the middle of the devices were formed by vacuum evaporation coating method. Effective area of the devices, the overlap section of the the electrode and the organic layer, is about 2mm2. To go through practical experience to optimize experimental parameters, and then obtained devices with good performance. The I-V characteristics in air and nitrogen dioxide gases of the two devices were respectively tested by KEITHLEY4200 semiconductor tester and gas measurement system, and the results were obtained and analyzed at last. By the test results, the two kinds of the devices showed good Schottky characteristics. When the devices were exposed in the environment of 10ppm NO2, their I-V characteristic curves had the trend of moving up over time. This is because the electron acceptor is affected by the acceptor doping. Along with the time increasing, the electron acceptor gradually increase to make the most carriers (holes) of the internal copper phthalocyanine increase. Above phenomenon leads to I-V characteristic curves move up. In addition, according to thermionic emission theory, the first device was discussed and analyzed. The barrier height when the device was in air and NO2 gas was obtained. It is discovered that the barrier height of CuPc/Al reduced 70meV when the device was exposed in NO2 gas for 28 minutes.
Keywords/Search Tags:copper phthalocyanine, Schottky, gas sensing property
PDF Full Text Request
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