氧化锌肖特基栅场效应晶体管制备及其紫外探测特性研究

ZnO Ultraviolet detectors have broad potential applications in UV light detection and UV image sensor fields, because of their excellent properties, including fast response speed, high quantum efficiency, large dynamic range and easy preparation in large area, etc. However, the lack of reliable and stable P type ZnO materials leads to conventional structures of reported ZnO detectors, which severely limits the development of high performance UV detectors. ZnO Schottky gate field effect transistors (ZnO MESFET) were proposed in this project. The transistors with epitaxy n-type ZnO active layer were fabricated on sapphire, and the Ohmic source (drain) electrodes and Schottky gate were prepared by lift-off technique. On the base of field effect theory, the transistors can obtain sensitive UV detection property by adjusting the depletion layer in active film. The electric field distribution in the active layer can be calculated by current-voltage model of the field effect transistor. The detection properties of the device can be investigated by adjusting structures, active layer deposition process and Schottky gate preparation process. These three terminal detectors have the advantages of Schottky diode fast response speed and transistor amplifying gain feature. It is not only expected to obtain UV detectors with high sensitivity, wide frequency band, fast response speed, also provided a new way for high resolution active array UV image sensors.

ZnO紫外探测器具有响应速度快、量子效率高、动态范围大、易于大面积制备等优点，在紫外探测和紫外图像传感领域有广阔的应用前景。然而稳定可靠的P型ZnO材料的缺失，致使目前研究的ZnO紫外探测器结构过于单一，严重限制了高性能紫外探测器的发展。本项目提出一种ZnO肖特基栅场效应晶体管（ZnO MESFET），即在蓝宝石衬底上外延N型ZnO薄膜作为有源层，采用剥离工艺在有源层上制作欧姆源漏电极和肖特基栅极。依据栅场效应原理，调控有源层中耗尽层状态，以获得高性能紫外探测器。利用场效应晶体管电流电压模型计算有源层中电场分布，并从理论和实验上综合考虑器件结构、有源层制备工艺、肖特基栅极制备工艺等对器件紫外探测性能的影响。这种三端子探测器集肖特基二极管快响应速度和晶体管放大增益特性于一体，不但预期获得高灵敏度、宽频带、快响应速度的紫外探测器，还可以为开发高分辨率有源阵列紫外图像传感器提供一种新的途径。

氧化锌紫外探测器在导弹预警、紫外通信、火焰探测等领域有非常广泛的应用前景，世界各国把紫外探测技术列为当今研究开发的重点课题。然而由于稳定的p型掺杂难于实现，限制了基于pn结型氧化锌紫外探测器的发展。本项目制备了一种三端子ZnO 肖特基栅场效应紫外探测器。即以高质量ZnO 薄膜为有源层，并在上面制作欧姆源漏电极和肖特基栅极，形成肖特基栅极场效应器件，并研究其紫外探测特性。本项目首先研究了高性能ZnO肖特基结的制备工艺，采用脉冲激光沉积和磁控溅射在玻璃衬底上制备ZnO半导体薄膜，然后在上面制备了Ag/ZnO肖特基结，电学测试费表明该结构具有良好的整流特性，在偏置电压为1V时的正反向电流比达到106，二极管理想因子为1.64，肖特基势垒高度为0.85 eV。我们研究了不同辐照强度下Ag/ZnO肖特基结的紫外光电特性。在这些研究基础上，我们制备了铝电极为源漏电极，银电极为栅极的肖特基栅极场效应晶体管,并研究了其紫外探测特性。以上研究为开发高性能栅压调控型三端子紫外探测器件提供了数据参考。