Mechanical strain engineering has been promising for many integrated photonic applications. However, for the engineering of a material electronic bandgap, a trade-off exists between the strain uniformity and the integration compatibility with photonic-integrated circuits (PICs). Herein, we adopted a straightforward recess-type design of a silicon nitride (${\mathrm{SiN}}_x$) stressor to achieve a uniform strain with enhanced magnitude in the material of interest on PICs. Normal-incidence, uniformly 0.56% tensile strained germanium (Ge)-on-insulator (GOI) metal-semiconductor-metal photodiodes were demonstrated, using the recessed stressor with 750 MPa tensile stress. The device exhibits a responsivity of $1.84\pm 0.15\mathrm{A}/\mathrm{W}$ at 1550 nm. The extracted Ge absorption coefficient is enhanced by $\sim 3.2\times$ to $8340{\mathrm{cm}}^{-1}$ at 1612 nm and is superior to that of ${\mathrm{In}}_{0.53}{\mathrm{Ga}}_{0.47}\mathrm{As}$ up to 1630 nm limited by the measurement spectrum. Compared with the nonrecess strained device, additional absorption coefficient improvement of 10%–20% in the $\mathrm{C}$-band and 40%–60% in the $\mathrm{L}$-band was observed. This work facilitates the recess-strained GOI photodiodes for free-space PIC applications and paves the way for various (e.g., Ge, GeSn or III-V based) uniformly strained photonic devices on PICs.

中文翻译：

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PIC 可集成、均匀拉伸应变的 Ge-on-insulator 光电二极管由凹陷的 SiN _x应力源实现

机械应变工程在许多集成光子应用中大有可为。然而，对于材料电子带隙的工程，应变均匀性和与光子集成电路 (PIC) 的集成兼容性之间存在权衡。在，我们采用了一种简单的氮化硅凹槽型设计（${罪}_X$) 应力源，以在 PIC 上感兴趣的材料中实现具有增强幅度的均匀应变。使用具有 750 MPa 拉伸应力的凹陷应力器演示了正常入射、均匀 ​​0.56% 拉伸应变的锗 (Ge) 绝缘体 (GOI) 金属-半导体-金属光电二极管。该设备表现出的响应性$1.84\pm 0.15\mathrm{一种。}/\mathrm{W。}$ 在 1550 nm 处。提取的 Ge 吸收系数增加了 $～3.2\times$ 至 $8340{\mathrm{厘米}}^{——1}$ 在 1612 nm 并且优于 ${在}_{0.53}{嘎}_{0.47}\mathrm{作为}$高达 1630 nm 受测量光谱的限制。与非凹槽应变装置相比，附加吸收系数提高了 10%-20%$\mathrm{C。}$-band 和 40% -60% 在 $\mathrm{L。}$-条带被观察到。这项工作促进了用于自由空间 PIC 应用的凹槽应变 GOI 光电二极管，并为 PIC 上的各种（例如，Ge、GeSn 或 III-V 基）均匀应变光子器件铺平了道路。