Silicon photodiodes are widely used in applications that require the measurement of the intensity, colour and position of visible light. Silicon is an attractive material for these systems owing to its low cost, low noise, and easy on-chip integration with read-out electronics. However, silicon cannot effectively be used to detect near-infrared (NIR, at wavelengths of 700–1,000 nm) light and short-wave infrared (SWIR, 1,000–1,700 nm) light because of its bandgap of 1.12 eV, which is equivalent to a wavelength of 1,100 nm. Here, we report silicon photodiodes based on hourglass-shaped silicon nanowires that use whispering-gallery-mode resonances to enhance their photoresponse in the NIR–SWIR region of the spectrum. The upper, inverted nanocone of the nanowires increases absorption probability by extending the dwell time of NIR–SWIR photons via the generation of whispering-gallery-mode resonances, whereas the lower nanocone with its low reflectance reabsorbs the light incident from surrounding nanowires. Our devices exhibit a higher responsivity and external quantum efficiency than existing silicon photodiodes at 700–1,100 nm. Furthermore, the responsivity at 1,000 nm is similar to that of commercial InGaAs photodiodes and light at 1,400 nm can also be detected. Using our devices, we demonstrate a heart-rate measurement system that offers performance comparable to commercial setups.

硅光电二极管广泛用于需要测量可见光的强度，颜色和位置的应用中。硅由于其低成本，低噪声以及易于与读出电子设备集成在芯片上，因此成为这些系统的诱人材料。但是，由于硅的带隙为1.12 eV，所以硅不能有效地用于检测近红外（NIR，在700–1,000 nm的波长下）光和短波红外（SWIR，在1,000–1,700 nm的光）下，这相当于1100 nm的波长。在这里，我们报告了基于沙漏形硅纳米线的硅光电二极管，该硅纳米线使用耳语画廊模式共振来增强其在光谱的NIR–SWIR区域中的光响应。上层，纳米线的倒置纳米锥通过耳语画廊模式共振的产生来延长NIR–SWIR光子的停留时间，从而增加吸收概率，而反射率较低的较低的纳米锥可吸收来自周围纳米线的光。我们的设备在700–1,100 nm处比现有的硅光电二极管具有更高的响应度和外部量子效率。此外，在1,000 nm处的响应度与商用InGaAs光电二极管相似，并且还可以检测到1,400 nm处的光。使用我们的设备，我们演示了一种心率测量系统，该系统可提供与商业设置相当的性能。我们的设备在700–1,100 nm处比现有的硅光电二极管具有更高的响应度和外部量子效率。此外，在1,000 nm处的响应度与商用InGaAs光电二极管相似，并且还可以检测到1,400 nm处的光。使用我们的设备，我们演示了一种心率测量系统，该系统可提供与商业设置相当的性能。我们的设备在700–1,100 nm处比现有的硅光电二极管具有更高的响应度和外部量子效率。此外，在1,000 nm处的响应度与商用InGaAs光电二极管相似，并且还可以检测到1,400 nm处的光。使用我们的设备，我们演示了一种心率测量系统，该系统可提供与商业设置相当的性能。