High-responsivity vertical-illumination Si/Ge uni-traveling-carrier photodiodes based on silicon-on-insulator substrate

• DOI: 10.48550/arxiv.1511.05593
• Publication Date: 2015-01-01
• Authors: Li, Chong; Xue, ChunLai; Liu, Zhi; Cong, Hui; Cheng, Buwen; Guo, Xia; Liu, Wuming
• Keywords: Condensed Matter - Materials Science; Physics - Instrumentation and Detectors; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; Instrumentation and Detectors (physics.ins-det); 7. Clean energy; Physics - Optics; Optics (physics.optics)

5pages,2figures<br/>Si/Ge uni-traveling carrier photodiodes exhibit higher output current when space-charge effects are overcome and thermal effects are suppressed, which is highly beneficial for increasing the dynamic range of various microwave photonic systems and simplifying high-bit-rate digital receivers in different applications. From the point of view of packaging, detectors with vertical-illumination configuration can be easily handled by pick-and-place tools and are a popular choice for making photo-receiver modules. However, vertical-illumination Si/Ge uni-traveling carrier (UTC) devices suffer from inter-constraint between high speed and high responsivity. Here, we report a high responsivity vertical-illumination Si/Ge UTC photodiode based on a silicon-on-insulator substrate. The maximum absorption efficiency of the devices was 2.4 times greater than the silicon substrate owing to constructive interference. The Si/Ge UTC photodiode was successfully fabricated and had a dominant responsivity at 1550 nm of 0.18 A/W, a 50% improvement even with a 25% thinner Ge absorption layer.<br/>