Abstract

We demonstrate p-type SiGe quantum well infrared photodetectors (QWIPs) on a strained-silicon-on-insulator (sSOI) substrate. The sSOI system allows strain-balancing between the QWIP heterostructure with an average composition of Si0.7Ge0.3 and the substrate, and therefore lifts restrictions to the active material thickness faced by SiGe growth on silicon or silicon-on-insulator substrates. The realized sSOI QWIPs feature a responsivity peak at detection wavelengths around 6 µm, based on a transition between heavy-hole states. The fabricated devices have been thoroughly characterized and compared to equivalent material simultaneously grown on virtual Si0.7Ge0.3 substrates based on graded SiGe buffers. Responsivities of up to 3.6 mA/W are achieved by the sSOI QWIPs at 77 K, demonstrating the large potential of sSOI-based devices as components for a group-IV optoelectronic platform in the mid-infrared spectral region.

Highlights

  • With the prospect of compact, robust and cheap integrated sensing and detection systems, the development of an optoelectronic group-IV-based platform for monolithic integration on a multifunctional chip continues to draw comprehensive research interest

  • Despite the relatively high dark-currents at finite bias, the large responsivity observed at zerobias allows competitive operation of the sSOI quantum well infrared photodetectors (QWIPs)

  • Responsivities of 1.7 mA/W are achieved at a dark-current density of 1.4 μA/cm2, which compares well to the figures reported for state-of-the-art SiGe QWIPs in literature [16,17,18]

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Summary

Introduction

With the prospect of compact, robust and cheap integrated sensing and detection systems, the development of an optoelectronic group-IV-based platform for monolithic integration on a multifunctional chip continues to draw comprehensive research interest. While work on siliconbased components for increased optical data transfer rates focuses on the telecommunication wavelength range [1,2,3,4,5,6,7,8,9,10], efforts towards an integrated sensing platform for novel lab-on-a-chip solutions target the mid-infrared regime [11,12,13,14,15] The latter is a well-known spectral fingerprint region including the vibrational and rotational absorption lines used to unambiguously identify chemical compounds. The devices were thoroughly characterized and compared to material simultaneously grown on conventional virtual substrates, demonstrating both excellent agreement between the QWIP bandstructure design and the responsivity characteristics as well as the superior performance of the sSOI devices as compared to those grown on a virtual substrate

Material growth and x-ray characterization
Device fabrication and band structure
Spectral characterization of the SiGe QWIP responsivity
Findings
Discussion and conclusions

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