Müller Raphael, Haertelt Marko, Niemasz Jasmin, Schwarz Klaus, Daumer Volker, Flores Yuri V, Ostendorf Ralf, Rehm Robert
Fraunhofer Institute for Applied Solid State Physics IAF, Tullastraße 72, 79108 Freiburg, Germany.
Micromachines (Basel). 2020 Dec 18;11(12):1124. doi: 10.3390/mi11121124.
We report on the development of thermoelectrically cooled (TE-cooled) InAs/GaSb type-II superlattice (T2SL) single element infrared (IR) photodetectors and exemplify their applicability for real-time IR spectroscopy in the mid-infrared in a possible application. As the European Union's Restriction of Hazardous Substances (RoHS) threatens the usage of the state-of-the-art detector material mercury cadmium telluride (MCT), RoHS-compatible alternatives to MCT have to be established for IR detection. We use bandgap engineered InAs/GaSb T2SLs to tailor the temperature-dependent bandgap energy for detection throughout the required spectral range. Molecular beam epitaxy of superlattice samples is performed on GaAs substrates with a metamorphic GaAsSb buffer layer. Photolithographic processing yields laterally-operated T2SL photodetectors. Integrated in a TE-cooled IR detector module, such T2SL photodetectors can be an alternative to MCT photodetectors for spectroscopy applications. Here, we exemplify this by exchanging a commercially available MCT-based IR detector module with our T2SL-based IR detector module in a real-time mid-infrared backscattering spectroscopy system for substance identification. The key detector requirements imposed by the spectroscopy system are a MHz-bandwidth, a broad spectral response, and a high signal-to-noise ratio, all of which are covered by the reported T2SL-based IR detector module. Hence, in this paper, we demonstrate the versatility of TE-cooled InAs/GaSb T2SL photodetectors and their applicability in an IR spectroscopy system.
我们报告了热电冷却（TE-cooled）的InAs/GaSb II型超晶格（T2SL）单元素红外（IR）光电探测器的研制情况，并举例说明了它们在一个可能的应用中用于中红外实时红外光谱的适用性。由于欧盟的有害物质限制（RoHS）威胁到最先进的探测器材料碲镉汞（MCT）的使用，因此必须为红外探测建立与RoHS兼容的MCT替代材料。我们使用带隙工程化的InAs/GaSb T2SL来调整与温度相关的带隙能量，以便在整个所需光谱范围内进行探测。超晶格样品的分子束外延是在具有变质GaAsSb缓冲层的GaAs衬底上进行的。光刻工艺可制造出横向操作的T2SL光电探测器。集成在TE冷却的红外探测器模块中，这种T2SL光电探测器可作为光谱应用中MCT光电探测器的替代品。在此，我们通过在用于物质识别的实时中红外背散射光谱系统中，将市售的基于MCT的红外探测器模块换成我们基于T2SL的红外探测器模块，来举例说明这一点。光谱系统对探测器提出的关键要求是兆赫兹带宽、宽光谱响应和高信噪比，所有这些要求所报道的基于T2SL的红外探测器模块都能满足。因此，在本文中，我们展示了TE冷却的InAs/GaSb T2SL光电探测器的多功能性及其在红外光谱系统中的适用性。
