Quartz microresonators for the high-resolution detection of infrared radiation

与频率相关的谐振式传感器适用于各种被测物的高分辨率检测，例如，通过石英微天平测量质量的最小变化或使用石英谐振器测量时间。各种出版物表明，这一原理也适用于温度测量，因此也适用于红外辐射的探测。高精度是由于准数字输出频率的干扰无关性和作为谐振器材料的石英良好的、长期稳定的机电性能。因此，与其他类型的红外探测器相比，噪声和其他干扰效应较低。这种谐振探测器的响应度(即温度变化引起的频率变化)与谐振频率成正比，该谐振频率随谐振结构的尺寸减小而增加。然而，一个限制因素是单晶石英的大尺寸(特别是石英厚度)。这导致较低的共振频率，从而导致从探测器元件到周围环境的较大热导值(与其他红外探测器相比)。虽然使用压电薄膜可以解决这一小型化问题，但由于其多晶特性导致了巨大的贡献过程，使得可实现的探测率仍然低于其他热红外传感器。因此，本文提出的项目的目标是制造具有典型尺寸的薄膜器件的3D结构、超薄(石英厚度&lt；5µm)的石英谐振器，同时避免多晶薄膜的缺点。因此，这种石英元件具有明显较小的热容和导热系数，从而提高了热分辨率和灵敏度以及探测率。为了降低热导，探测器元件被设计为自支撑的，并由蚀刻沟槽隔热。通过引入到晶体中的沟槽实现了探测器系统的灵敏度的进一步提高。结果，由于质量较低，石英振荡器的谐振频率增加。生产是通过离子束刻蚀的方式进行的。最后，传感器元件的吸收率应该通过超薄的纳米结构的黑色层来增加。它们是由相应的黑层物质掠角蒸发而产生的。通过分析模型和数值模拟，推导出设计准则，利用这些准则可以获得最大可能的探测值。为了评估新的方法，应该构建演示器，并根据其灵敏度和噪声行为对其进行表征。

Frequency-dependent, resonant sensors are suitable for the high-resolution detection of a variety of measurands, e.g. for measuring smallest changes in mass by means of quartz microbalances or for time using quartz resonators. Various publications have shown that this principle is also suitable for the temperature measurement and, hence, for the detection of infrared radiation. The high accuracy results from the interference independence of the quasi-digital output frequency and the excellent, long-term stable electromechanical properties of quartz as resonator material. For that reason, noise and other interfering effects are low compared to other IR detector types. The responsibility (i.e. the change in frequency caused by temperature change) of such resonance detectors is proportional to the resonance frequency, which increases with decreasing size of the resonating structure. However, a limiting factor is the large dimension of the monocrystalline quartz (in particular quartz thickness). This results in low resonance frequencies and, thus, in large thermal conductance values (compared to other IR detectors) from the detector element to the surroundings. Although the use of piezoelectric thin films could solve this miniaturization problem, the polycrystalline properties lead to huge contributions processes so that the achievable detectivity would remain below that of other thermal IR sensors.Therefore, the goal of the project proposed here is to create 3D-structured, ultra-thin (quartz thickness < 5 µm) quartz resonators that have typical dimensions of thin-film devices but avoid the disadvantages of polycrystalline thin films. As a result, such quartz elements have significantly smaller heat capacities and thermal conductivities, which increases both the thermal resolution and the sensitivity as well as the detectivity. To reduce the thermal conductance, the detector element is designed to be self-supporting and thermally insulated by an etching trench. A further increase in sensitivity of the detector system is achieved by means of trenches which are introduced into the crystal. As a result, the resonant frequency of the quartz oscillator increases due to the lower mass. The production takes place by means of ion beam etching. Finally, the absorptivity of the sensor element should be increased by ultra-thin nanostructured black layers. These are produced by glancing angle evaporation of corresponding black layer materials. By means of analytical models and numerical simulations design guidelines are to be derived with which the greatest possible detectivity values can be achieved. To evaluate the novel approach, demonstrators should be constructed and characterized regarding their sensitivity and their noise behavior.