The Influence of Photosensitive Pixel Size on the Photocurrent of InGaAs Photodetectors

InGaAs光电探测器因其优异的短波红外响应特性、低暗电流和高响应度，在红外成像、激光通信和光谱检测等领域具有广泛应用。光敏元作为探测器的核心结构，其面积大小不仅影响光通量的吸收效率，还关系到器件的空间分辨率和光电性能。然而，光敏元面积对光电流特性的具体影响规律仍需系统实验验证。为此，本文设计并制备了光敏元面积从30 × 30 μm2至500 × 500 μm2的InGaAs探测器样品，测试并分析了其在暗态和光照条件下的电流–电压(I-V)特性。结果表明，随着光敏面积的增加，光电流呈明显增强趋势，且I-V曲线形状保持一致，反映出材料制程的一致性。在暗态下，暗电流随光敏元面积的增大而增大，但单位面积暗电流密度基本稳定，说明其主要来源为体电流。在光照条件下，不同面积器件的光电流接近线性增长，验证了光敏面积对光响应能力的直接影响。研究结果为InGaAs光电探测器在高分辨率与多像元集成应用中的结构设计提供了重要参考。This InGaAs photodetector, with its excellent short-wavelength infrared response, low dark current, and high responsivity, has been widely applied in infrared imaging, laser communication, and spectral detection. As the core structure of the detector, the area of the photosensitive element not only affects the efficiency of light flux absorption but also relates closely to the spatial resolution and photoelectric performance of the device. However, the specific influence of the photosensitive area on photocurrent characteristics still requires systematic experimental verification. To this end, this study designs and fabricates InGaAs detector samples with photosensitive areas ranging from 30 × 30 μm2 to 500 × 500 μm2, and investigates their current-voltage (I-V) characteristics under both dark and illuminated conditions. The results show that as the photosensitive area increases, the photocurrent exhibits a significant rising trend, while the overall I-V curve shape remains consistent, reflecting the uniformity of the material fabrication process. Under dark conditions, the dark current increases with the photosensitive area, but the dark current density per unit area remains nearly constant, indicating that the primary source is bulk current. Under illumination, the photocurrent of devices with different areas increases nearly linearly, confirming the direct impact of the photosensitive area on light response capability. These findings provide valuable reference for structural design in high-resolution and multi-pixel integrated applications of InGaAs photodetectors.