【作者】 刘畅；

【导师】 龚敏；

【作者基本信息】 四川大学 ， 凝聚态物理， 2004， 硕士

【摘要】 氮化镓(GaN)半导体材料是第三代宽禁带化合物半导体材料的重要代表之一。它及其相关合金系Al-In-Ga-N所具有的宽带隙范围，优良的光、电学特性使其在蓝、绿光到紫外光波段的发光器件、紫外探测器、蓝色激光器、外空间和海底通讯电子器件以及特殊条件下的半导体器件等领域有着广泛的应用前景。基于GaN的强抗辐照能力，国内外许多研究机构加大力度研究其辐照效应。他们着眼于研究GaN材料在辐照后的缺陷变化，而对GaN器件辐照损伤的报道较少，尤其是关于GaN光敏器件的电子辐照损伤的研究几乎没有。 本文首先观察到商用GaN肖特基紫外探测器(Optoway．Inc，OUVC1-GNA2)在小注量的电子辐照后出现辐照失效的现象。利用SEM，XPS和AFM对该探测器进行成分分析，并制作了与此GaN肖特基紫外探测器结构类似的GaN肖特基二极管用于研究它的失效机理。 通过Ⅰ-Ⅴ测试技术，观察到在1MeV的小注量电子辐照后，GaN肖特基二极管的电流—电压特性退化，击穿电压明显减小，反向漏电流逐渐增大。证实了GaN肖特基势垒光敏器件的辐照失效与界面态有关，而不是由GaN体材料中的缺陷导致的。由于pn结探测器不存在界面态，因此，可使用pn结结构代替肖特基势垒来解决辐照失效现象。 用不同波长(380nm和254nm)的紫外光和可见光照射GaN肖特基二极管，用以研究二极管对不同波长光的光敏特性的变化。辐照前，只有254nm紫外光照射二极管引起反向复合电流的变化。不同程度的注量辐照后，紫外光380nm和可见光照射下二极管的Ⅰ-Ⅴ特性出现变化。说明辐照效应将导致肖特基势垒光敏器件对较长波长的吸收，使得UV探测器中可见光成分的背景噪声增加。这种辐照效应导致的GaN肖特基势垒二极管光敏性能下降的失效机理也应存在于Pn结型的光敏器件中。 关键词:GaN肖特基紫外探测器电子辐照肖特基二极管辐照失效金属/半导体界面更多还原

【Abstract】 Gallium nitride (GaN) is one of the promising wide bandgap compound semiconductor materials. Ill-nitride compound semiconductor covers the ultraviolet to visible spectral region. Amongst these, it shows unique applications in green, blue or ultraviolet light emitting diodes (LED ), lasers and detectors. Low thermal carrier generation rates and large critical breakdown field make them attractive for the development of electronic devices capable of reliable operation under extreme conditions, such as high power, high temperature and in nuclear environment of the outer space. Recently, several groups have investigated the effect of high energy irradiation on the material properties of GaN. However, there are relatively few reports on the effects of high-energy irradiation on the electrical characteristics of GaN-based device.The electron irradiation damage of GaN Schottky UV detector (Optoway. Inc, 0UVC1-GNA2) has been observed. The structure of the detector has been analyzed using SEM, XPS and AFM. According to the analysis of the structure, GaN Schottky diodes have been made to study the reason of electron irradiation-induced damage.The effects on I-V characteristics observed in the Schottky diodes indicated that even a light-dose irradiation would obviously reduce the reverse breakdown voltage but slightly enlarge the reverse leakage current. The reason that the irradiation induced failure of GaN devices was due to the damage of Au/GaN Schottky interface. This mechanism of the failure may not exist in pn junction type detectors.The effects of irradiation on the UV and visible lights sensitive characteristics ofGaN Schottcky barrier devices also have been investigated using current-voltage (I-V) measurement. After irradiation, the light of UV (380nm) and even visible light, could be detected. The energies of these photons are smaller than the bandgap (3.4eV) of GaN and the lights should not be detected before irradiation. The effects of electron irradiation led to the increasing of visible light background yawp in Schottcky barrier UV detector. This failure mechanism, due to the induced shallow-levels, may be also observed in pn junction photosensitive devices.更多还原