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Band Structure Design and Photoelectric Characteristics of GaAs/GaN Dual-Band Detect Film

Author: WangDongBo
Tutor: GuoFengYun
School: Harbin Institute of Technology
Course: Materials Physics and Chemistry
Keywords: GaAs / GaN films MBE Voltage characteristics Photoresponse
CLC: TB383.2
Type: Master's thesis
Year: 2009
Downloads: 48
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Abstract


To achieve the purpose of the two-color detection, we are probing the structural design of the thin film material, of the two materials of the GaAs and GaN epitaxial growth together form heterojunction thin film, the use of GaN interband absorption, ultraviolet detection, the same time, the use of GaAs free carrier sub-signal absorption of infrared light by the the heterojunction band (barrier height) of the infrared-ray detecting binding effect. To this end, the band structure and optoelectronic properties of GaAs / GaN two-color detection film. GaAs / GaN thin films prepared by MBE technology, and GaAs / GaN crystalline quality of the films was analyzed by X-ray diffraction methods. Keithley 617 optical characteristic measuring instrument to test the voltage characteristics of thin film materials, through theoretical analysis and experimental results reveal a GaAs / GaN film band structure and carrier transport mechanism. By VERTEX70 photocurrent spectrum measuring instrument test the photoelectric response characteristics of thin-film materials, photoelectric response mechanism to clarify the different spectral regions analyzed through theoretical calculations and experimental results. The volt-ampere characteristics of pn-and nn-type GaAs / GaN film voltammetry characteristic curves showed good rectifying characteristics. The IV curve of the experimentally measured and simulated curves are similar, the film band structure to meet the design. Analyzed by the film volt-ampere characteristics of the two types of GaAs / GaN film band structure. On the volt-ampere characteristic curve fitting the film carrier transport mechanism. pn-type GaAs / GaN film below 0.2V ,0.2-2 .8 V composite mechanism of diffusion and thermal electron emission tunnel complex mechanism for hot electron emission. Above 2.8V tunneling mechanism to play a major role. nn-type GaAs / GaN film 0.3V below the thermal electron emission and diffusion bonding mechanism, 0.3V-3V thermal electron emission and tunneling composite mechanism. The tunneling mechanism to play a major role in the above 3V. Photoelectric response characteristics of two types of GaAs / GaN films in the ultraviolet region have good photoelectric response, and the an nn type of GaAs / GaN thin films in the ultraviolet region response is stronger than the pn-type GaAs / GaN film. Under forward bias in the infrared region, the pn-type GaAs / GaN thin film has good photoelectric response. With the forward voltage increases detection cutoff wavelength blue shift. nn-type GaAs / GaN film under a negative bias a better photoresponse cutoff wavelength, probing with the negative voltage increases to the long direction of the mobile. Use with the design of the infrared region of the GaAs free carrier absorption of the infrared light signals by the heterojunction band (barrier height) of the binding effect of the photoelectric detection of the infrared light signal response mechanism consistent. Further, pn-type GaAs / GaN film plus the forward bias voltage in GaAs free carriers over the barrier formation while responding in GaN electrons also in the voltage stress caused by tunneling effect tunneling current to form a noise. nn-type GaAs / GaN film negative bias only free carriers in GaAs across the barrier formation response in GaN electronic shackled its photocurrent spectrum background current (noise) was significantly lower than the pn-type GaAs / GaN films.

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