We report resonant cavity infrared detectors with a peak wavelength of 4.54–4.58 μm that combine external quantum efficiency (EQE) exceeding 70% with spectral bandwidth 20–40 nm and ≤2% EQE at all non-resonance wavelengths between 4 and 5 μm. A 300-nm-thick absorber assures that most of the radiation propagating in the cavity produces photocurrent rather than parasitic loss. The cavity is formed by heterogeneously bonding a midwave infrared (MWIR) nBn detector chip to a GaAs/AlGaAs distributed Bragg reflector, etching away the GaSb substrate, forming mesas with diameter ≈100 μm, depositing a Ge spacer, and then depositing a single-period Ge-SiO2 top mirror. At all temperatures between 125 and 300 K, the responsivity at 150 mV bias exceeds 2.2 A/W and the EQE exceeds 61%. When the thermal background current for a realistic system scenario with f/4 optic that views a 300 K scene is derived from the observed EQE spectra, the resulting specific detectivity D* of 7.5 × 1012 cmHz½/W at 125 K operating temperature is 4.5 times higher than for a state-of-the-art broadband MWIR HgCdTe device. Simulations of the cavity performance indicate that EQE > 90% may be feasible following minimization of parasitic optical loss and maximization of the photocarrier collection efficiency. Potential applications include free space optical communication, chemical sensing, on-chip spectroscopy, and hyperspectral imaging.

中文翻译：

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量子效率为 >70% 的中波红外谐振腔探测器


我们报道了峰值波长为 4.54-4.58 μm 的谐振腔红外探测器，其外部量子效率 （EQE） 超过 70%，光谱带宽为 20-40 nm，在 4 至 5 μm 之间的所有非谐振波长下 EQE 为 ≤2%。300 nm 厚的吸收器可确保在腔中传播的大部分辐射产生光电流，而不是寄生损耗。该腔体是通过将中波红外 （MWIR） nBn 探测器芯片异构粘合到 GaAs/AlGaAs 分布式布拉格反射器上，蚀刻掉 GaSb 衬底，形成直径为 ≈100 μm 的台面，沉积 Ge 垫片，然后沉积单周期 Ge-SiO2 顶镜而形成的。在 125 至 300 K 之间的所有温度下，150 mV 偏置时的响应度超过 2.2 A/W，EQE 超过 61%。当使用观察 f/4 光学器件观察 300 K 场景的真实系统场景的热背景电流从观察到的 EQE 光谱中得出时，在 125 K 工作温度下得到的 7.5 × 1012 cmHz1/2/W 的比探测率 D* 比最先进的宽带中波红外硫化镉化镉器件高 4.5 倍。腔体性能的模拟表明，在寄生光损耗最小化和光载流子收集效率最大化后，EQE > 90% 可能是可行的。潜在应用包括自由空间光通信、化学传感、片上光谱和高光谱成像。