【摘要】 短波红外探测技术在天文观测中具有重要的应用。红外天文观测的目标辐射信号较弱，要求红外探测器需具备极低的暗电流和读出噪声以及高量子效率。针对国内红外天文观测对红外探测器的应用需求，文中开展了天文用短波碲镉汞红外焦平面探测器的研究。采用液相外延技术进行材料生长，通过在器件表面形成高镉（Cd）组分的钝化层和对读出电路进行优化设计来抑制暗电流，研制出了像元中心距15μm的极低暗电流640×512短波碲镉汞红外焦平面探测器，并基于“光子转移曲线”的测试方法对探测器进行了系统的表征。测试结果显示，液氮温度下探测器的截止波长为2.8μm，器件暗电流为4.7 e^-/s·pixel^-1，读出噪声为65 e^-，K波段量子效率达到85%，满阱电荷量为97 340 e^-，有效像元率达到99.4%。在冷湖中山大学80 cm红外望远镜进行了外场观测实验，在20 s的积分时间下，探测器单次成像灵敏度在K波段达到15.1 mag，与国际著名的2MASS近红外巡天的成像灵敏度相当。以上结果表明该探测器的性能指标满足地基红外天文观测需求，具备了在天文K波段进行观测的能力。该研究成果将为国内红外天文领域的发展提供有力的技术支持。更多还原

【Abstract】 Objective Infrared astronomical observation serves as a vital technical means for exploring the universe. The short-wave infrared band, which bridges the visible and mid-infrared ranges, carries extremely rich spectral information from the cosmos and constitutes an indispensable window for astrophysical research. Unlike conventional Earth observation, the extreme faintness of astronomical targets demands detectors with extremely low dark current and readout noise. Due to a relatively late start and the early lack of major astronomical project drivers, progress in the development of astronomical infrared detectors in China has been relatively slow, with device performance primarily limited by dark current and readout noise. In recent years, with the advancement of major national projects such as the Chinese Space Station Telescope, the demand for domestically produced astronomical infrared detectors has grown increasingly urgent. Therefore, this paper conducts a study on the shortwave Hg Cd Te infrared focal plane array used for astronomical observations.Methods The Hg Cd Te material was grown using liquid-phase epitaxy, and the device employs an n-on-p structure（as shown in Fig.1）. P-type doping of the material was achieved through high-temperature annealing,while n-type doping was realized via boron ion implantation to form the p-n junction. A gradient passivation layer with high Cd composition was formed on the device surface to suppress surface leakage current. The device was interconnected with a designed readout integrated circuit（ROIC） via flip-chip bonding, resulting in a focal plane array with a format of 640×512 and a pixel pitch of 15 μm. The detector was systematically characterized at liquid nitrogen temperature using the photon transfer curve（PTC） method. Figure 2 shows a schematic diagram of the infrared focal plane array test system used in this study.Results and Discussions At liquid nitrogen temperature, the detector exhibits a dark current of 4.7??e^-/s·pixel^-1（Fig.5）,representing a reduction of over an order of magnitude compared to the level before device fabrication process optimization. The readout noise is 65??e-（Fig.7）, and the cutoff wavelength is 2.8??μm（Fig.8）. The quantum efficiency in the K-band reaches 85%, which is comparable to reported values for astronomical short-wave infrared detectors. The full-well capacity is 97 340 e-and the effective pixel operability is 99.4%（Fig.11）. Field observation results indicate that the detector achieves an observation sensitivity of 15.1 mag with an integration time of 20 s. The sensitivity of the detector is primarily limited by sky background noise, the detector’s own readout noise and dark current are not the bottleneck for the overall observational performance of the telescope.Conclusions In this paper, we report a short-wave infrared focal plane with a 640 pixel×512 pixel array format,15 μm pixel pitch. The device was fabricated based on liquid-phase epitaxial Hg Cd Te material. Dark current was suppressed by forming a high-Cd-composition passivation layer on the device surface and optimizing the power consumption of the readout circuit. When operated at liquid nitrogen temperature, the detector demonstrates a cutoff wavelength of 2.8 μm, a dark current of 4.7 e^-/s·pixel^-1, a readout noise of 65 e^-, a K-band quantum efficiency of 85%, a full-well capacity of 97 340 e^-, and an effective pixel operability of 99.4%. Field observation results indicate that the detector achieves an observation sensitivity of 15.1 mag with an integration time of 20 s.These results demonstrate that the detector’s performance meets the requirements for ground-based astronomical K-band observations. Future work will initially focus on optimizing the detector’s readout noise. In addition, given that the mainstream international astronomical Hg Cd Te infrared focal plane array is currently based on the p-on-n structure, parallel research on p-on-n short-wave Hg Cd Te infrared focal plane array will also be carried out to explore methods for further reducing dark current. On this basis, research on larger-format astronomical infrared focal plane array will be conducted.更多还原