We present a novel ultrathin avalanche photodiode (APD) with a silicon (Si) body thickness of 640 nm and optimized doping profiles to significantly improve the detection efficiency in ultraviolet (UV) spectral range from near UV (NUV) to UV-C (here studied down to 275 nm). The square photodiode is fabricated on silicon-on-insulator (SOI) substrate with an active area of $420~ \mu \text{m}^{2}$ ( $37\,\, \mu \text{m}\,\,\times 37\,\, \mu \text{m}$ ) consisting of n⁺⁺/p-well and an n-well guard ring (GR). The dark current–voltage ( ${I} - {V}$ ) characteristic exhibits low leakage current (≈pA) and breakdown voltage of 8.6 V. A peak quantum efficiency (QE) of 93.88% is obtained on a wavelength of 400 nm at 4 V. An outstanding expansion of the sensitivity in UV-C is presented with a QE of 82.75% under a wavelength of 275 nm at 4 V. With a gain value of 4.9, a responsivity of 14.46 A/W at a wavelength of 400 nm on a low-level light intensity of $3.28~ \mu \text{W} {/}$ cm² is achieved at 7.8 V. A sufficient detection performance in visible spectral range has also been achieved due to the formation of the sandwiched thin silicon body between nearly 200-nm SiO₂ on top and 1- $ \mu \text{m}$ buried SiO₂ (BOX). This proposed ultrathin photodiode indicates a potential high avalanche gain (>10⁵) in Geiger mode.

中文翻译：

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基于 SOI 技术的具有 640 nm 薄硅体的增强型紫外雪崩光电二极管

我们提出了一种新型超薄雪崩光电二极管 (APD)，其硅 (Si) 体厚度为 640 nm，并优化了掺杂分布，以显着提高从近紫外 (NUV) 到 UV-C 的紫外 (UV) 光谱范围内的检测效率（此处为研究到 275 nm）。方形光电二极管制作在绝缘体上硅 (SOI) 衬底上，有源面积为 $420~ \mu \text{m}^{2}$ ( $37\,\, \mu \text{m}\,\,\times 37\,\, \mu \text{m}$ ) 由 n ⁺⁺ /p-well 和 n-well 保护环 (GR) 组成。暗电流-电压（ ${I} - {V}$ ) 特性表现出低漏电流 (≈pA) 和 8.6 V 击穿电压。在 4 V 波长 400 nm 上获得 93.88% 的峰值量子效率 (QE)。UV-C 中灵敏度的显着扩展是在 4 V 的 275 nm 波长下具有 82.75% 的 QE。增益值为 4.9，在 400 nm 波长下对低电平光强度的响应率为 14.46 A/W $3.28~ \mu \text{W} {/}$ cm ²在 7.8 V 下实现。由于在顶部近 200 nm SiO ₂和 1- SiO ₂之间形成夹心薄硅体，因此在可见光谱范围内也实现了足够的检测性能。 $ \mu \text{m}$ 掩埋 SiO ₂ (BOX)。这种提议的超薄光电二极管表明在盖革模式下具有潜在的高雪崩增益 (>10 ⁵ )。