Thinning of Cascaded Multiplication Layers in Avalanche Photodiodes for High-Speed and High-Power-Tolerant Performance

The thinning of the multiplication (M) layers in high-speed avalanche photodiodes (APDs) is an effective way to boost the gain-bandwidth product (GBP) and reduce excess noise. However, such downscaling usually comes at the price of a huge leakage current (>1 μA) induced by direct tunneling through the final thin M-layer (<100>0.52 Al _0.48 As based multiplication layer can effectively relax the trade-offs among the dark current, RC-limited bandwidth, multiplication gain, and avalanche delay time. This advanced device structure is then applied and the performance of APDs with different thin M-layer thicknesses (<50>br . This device also exhibits excellent dynamic performance, including a wide optical-to-electrical bandwidth (44 GHz at 0.84 A/W), an extremely large GBP of 1.03 THz, and a high saturation current (12 mA), which corresponds to a large millimeter-wave (MMW) output power (∼0 dBm) at 45 GHz. The exceptional speed performance coupled with the wide dynamic range and simple top-illuminated structure opens up new possibilities to further enhance the sensitivity of 50 G passive optical networks (PONs).