Enhancement in speed and responsivity of uni-traveling carrier photodiodes with GaAs0.5Sb0.5/In0.53Ga0.47As type-II hybrid absorbers

Naseem, Zohauddin Ahmad, Rui Lin Chao, Hsiang Szu Chang, C. J. Ni, H. S. Chen, Jack Jia Sheng Huang, Emin Chou, Yu Heng Jan, Jin Wei Shi

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


We demonstrate a top-illuminated high-speed uni-traveling carrier photodiode (UTC-PD) with a novel design in the p-type absorber, which can effectively shorten the photon absorption depth at telecommunication wavelengths (1.31∼1.55 μm) and further enhance the bandwidth-efficiency product of UTC-PD. In our proposed new UTC-PD structure, the p-type In0.53Ga0.47As absorption layer is replaced by the type-II GaAs0.5Sb0.5 (p)/In0.53Ga0.47As (i) hybrid absorber. Due to the narrowing of the bandgap and enhancement of the photo-absorption process at the type-II interface between the GaAs0.5Sb0.5 and In0.53Ga0.47As layers, our device shows an over 16.7% improvement in the responsivity compared with that of UTC-PD with the same thickness of pure In0.53Ga0.47As absorber (0.7 μm) and a zero optical coupling loss. Our demonstrated device with a simple top-illuminated structure offers a large active mesa (25 μm), a wide optical-to-electrical (O-E) bandwidth (33 GHz), a high responsivity (0.7 A/W), and a high saturation current (>5 mA) under 1.31 μm optical wavelength. These promising results suggest that our proposed PD structure can fundamentally overcome the trade-off among bandwidth, efficiency, and device active diameter of high-speed PDs.

Original languageEnglish
Pages (from-to)15495-15504
Number of pages10
JournalOptics Express
Issue number11
StatePublished - 2019


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