Dissertation > Excellent graduate degree dissertation topics show

Electrical Transport Properties of the Amorphous Carbon/Silicon Heterojunctions Fabricated by Magnetron Sputtering

Author: GaoXiLi
Tutor: XueQingZhong
School: China University of Petroleum
Course: Materials Physics and Chemistry
Keywords: heterojunction electrical property gas pressure sensitivity ammonia sensitivity
CLC: O484
Type: Master's thesis
Year: 2008
Downloads: 137
Quote: 1
Read: Download Dissertation

Abstract


Amorphous carbon film/n-Si （a-C/n-Si） heterojuctions were fabricated by magnetron sputtering, and their electrical characteristics, gas pressure sensitivity and ammonia gas sensitivity have been investigated.The current-voltage （I-V） characteristics and temperature dependence of the a-C/n-Si heterojunctions have been investigated. The results show that these junctions have good rectifying properties in the temperature range 80300 K. The interesting result is that the current-voltage curve changes dramatically with increasing applied voltage and temperature. For the forward bias voltages, the junction shows Ohmic mechanism characteristic in the temperature range 240300 K. However, the conduction mechanism changes from Ohmic for the low bias voltages to space charge limited current for the high bias voltages in the temperature range 80240 K. While for the reverse bias voltages, it changes from Schottky emission to breakdown with increasing voltage. Another important phenomenon is that the temperature dependence of the junction resistance shows a metal-insulator transition, whose transition temperature can be controlled by the bias voltage. A possible mechanism is given to understand the abnormal electrical properties.The results show that the gas pressure has a large effect on the reverse bias I-V characteristics of the junctions. For a given reverse bias voltage, the reverse current can increase by 3300 % when the gas pressure decreases from 100000 Pa to 100 Pa. Moreover, the deposition temperature and gas pressure have a large effect on the a-C/Si junctions’sensitivity. The results indicate that the sample deposited at 4 Pa and 300 K which has the largest gas pressure sensitivity. The effect of gas pressure may be attributed to the physisorption process of gas molecules which increases the space charge width and changes the surface states of the junction. This study shows that the a-C/Si junctions have potential application as gas pressure sensors. An approach to detect NH3 gas at room temperature was demonstrated by using simple a-C/Si junctions. The results show that the a-C/Si junctions have immediate response, high sensitivity and good reproducibility for NH3 gas detection. For a given reverse bias voltage,the resistance of the junction can increase by 100 times rapidly when exposed to NH3 gas. Moreover, the resistance of the junction recovers rapidly when the junction is transferred from NH3 gas to air. The results show that these junctions have immediate response, high sensitivity and good reproducibility for NH3 gas detection. This phenomenon may be attributed to the change of the space charge width of the junction, which is caused by the adsorption of NH3 gas molecules. This study shows that these a-C/Si junctions have potential application as NH3 gas detect sensors.

Related Dissertations

  1. ZnSe / Si heterojunction Nanowires,TB383.1
  2. The Research of Pressure on Mosfet Transconductance Modulation,TN386.1
  3. Research on Zinc Oxide Varistors Doped with Rare Earth Oxides,TM54
  4. Fabrication and Electrical Characteristics of Doped Large Grain Polycrystalline Silicon Films,TM914.42
  5. Microstructure, Magnetic and Transport Properties of Fe3O4 Based Heterostructures,TN304.21
  6. Investigation of Ferroelectric/Oxide Heterojunction Integration and Related Devices,O484.1
  7. Characteristics of aluminum-doped zinc oxide films,O484.4
  8. Floating method and anodic alumina template - assisted CVD carbon nanotubes prepared,TB383.1
  9. Electrical Properties of ZnS / silicon nanoporous pillar array heterostructure,TB383.1
  10. Synthesis and Characteristics Research of ZnO/Cu2O Heterojunction Nanowire,TB383.1
  11. The Synthesis of SiNWs-ZnO Heterojunction Arrays and Their Humidity Sensitivity Studied,TB383.1
  12. Physical Properties and Controllable Synthesis of 3-dimensional ZnO Nanostructures,TB383.1
  13. Synthesis and Photovoltaic Properties of the Thienyl Benzothiadiazole Organic Small-molecule and Copolymers Donor Materials,TM914.4
  14. Studies on the Synthesis and Characterization of Cross-linkable Bulk -heterojunction Solar Cell Materials,TM914.4
  15. The Simulation and Reasearch of AlGaN/GaN HEMT,TN325
  16. Synthesis and Characterization of ZnO and ZnS Nanomaterials Produced Via Vapor-deposition Method,TB383.1
  17. Synthesis and Studies on the Properties of Bi (Ⅲ), Cu (Ⅰ) Series Photocatalyst,X703
  18. CdS/ZnO Heterostructure: Fabrication and Photoelectrochemical Properties,TB383.1
  19. Investigation of Bismuth Titanate Derived Ferroelectric Films,O484.4
  20. Study of Structure and Optical Characteristics of GaAs/GaN Grown by Molecular Beam Epitaxy,TN304.055
  21. GaN-based double heterojunction characteristics,TN304.2

CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Thin Film Physics
© 2012 www.DissertationTopic.Net  Mobile