All‐Group IV Transferable Membrane Mid‐Infrared Photodetectors

Abstract

Semiconductor membranes emerged as a versatile class of nanomaterials to control lattice strain and engineer complex heterostructures enabling a variety of innovative applications. With this perspective, herein this platform is exploited to tune simultaneously the lattice parameter and bandgap energy in group IV GeSn semiconductor alloys. As Sn content is increased to reach a direct bandgap, these semiconductors become metastable and typically compressively strained. It is shown that the relaxation in released membranes extends the absorption wavelength range deeper in the mid-infrared. Fully released Ge 0.83 Sn 0.17 membranes are integrated on silicon and used in the fabrication of broadband photodetectors operating at room temperature with a record wavelength cutoff of 4.6 µm, without compromising the performance at shorter wavelengths down to 2.3 µm. These membrane devices are characterized by two orders of magnitude reduction in dark current as compared to as-grown strained epitaxial layers. A variety of experimental tools and optimized calculations are used to discuss the crystalline quality, composition uniformity, lattice strain, and the electronic band structure of the investigated materials and devices. The ability to engineer all-group IV transferable mid-infrared photodetectors lays the groundwork to implement scalable and flexible sensing and imaging technologies exploiting these integrative, silicon-compatible strained-relaxed GeSn membranes.

Midinfrared Emission and Absorption in Strained and Relaxed Direct-Band-Gap Ge1−xSnx Semiconductors

“…Additionally, these analyses also demonstrate the band-gap directness in strained and relaxed Ge 0.83 Sn 0.17 layers as well is in the compositionally graded Ge 0.863 Sn 0.137 . Thus, the control of both strain and composition uniformity is highly useful for engineering the emission operational range and linewidth in 024031-11 Ge 1-x Sn x optoelectronic devices [17]. Applications requiring a narrower spectral range would benefit from the use of uniform, Ge 1-x Sn x layers, where a large amount of Sn can be incorporated while avoiding phase segregation [49].…”

“…This process was exploited in recent studies demonstrating roomtemperature optical emission down to 0.36 eV (approximately 3.4 μm wavelength) [4], as well as optically and electrically pumped lasers at short-wave IR (SWIR)-MIR wavelengths operating at lower temperatures [11][12][13]. Postgrowth control and manipulation of strain have also been utilized to extend the emission range as longer emission wavelengths can be achieved through relaxation and tensile-strain engineering [2][3][4]11,[14][15][16][17].…”

Simulation of High-Efficiency Resonant-Cavity-Enhanced GeSn Single-Photon Avalanche Photodiodes for Sensing and Optical Quantum Applications

“…The parameters of GeSn alloys are calculated by linear interpolation of parameters of Ge and α-Sn except bandgaps. The bandgaps of unstrained GeSn alloy are described by quadratic polynomials including bowing parameters (bΓ = 2.18 eV and bL = 0.68 eV) [25].…”

High-Bandwidth Extended-SWIR GeSn Photodetectors on Silicon Achieving Ultrafast Broadband Spectroscopic Response

“…It is worth mentioning that the high responsivity at low dark current and low bias should significantly increase the detectivity of these devices as compared to photoconductive devices that suffer from high dark current and high noise. 29,30 This would allow the operation of GeSn PIN devices without the need for lock-in technique to extract the photocurrent signal.…”