High carrier lifetimes in epitaxial germanium–tin/Al(In)As heterostructures with variable tin compositions

Abstract

Group IV-based germanium-tin (Ge1-ySny) compositional materials have recently shown great promise for infrared detection, light emission and ultra-low power transistors. High carrier lifetimes are desirable for enhancing the detection limit...

Lattice matched GeSn/InAlAs heterostructure: role of Sn in energy band alignment, atomic layer diffusion and photoluminescence

“…The material synthesis, compositional and structural analysis of these heterostructure materials systems are discussed elsewhere. 31 Wherein it was shown using high-resolution X-ray diffraction that the GeSn epitaxial layers were of coherent crystalline quality, and the lattice matched sample D had a narrower reciprocal lattice point contour than the compressively strained samples B (B0.53% strain) and C (B0.81% strain), conforming to the need of growing a lattice matched GeSn epitaxial layer. Also characterized were the effective carrier lifetimes of the GeSn epitaxial layers using microwave reflection photoconductive decay technique (m-PCD) probed at 300 K to extract carrier lifetimes of 220 ns, 468 ns and 324 ns for samples B, C and D, respectively.…”

“…Also characterized were the effective carrier lifetimes of the GeSn epitaxial layers using microwave reflection photoconductive decay technique (m-PCD) probed at 300 K to extract carrier lifetimes of 220 ns, 468 ns and 324 ns for samples B, C and D, respectively. 31 These material characterization techniques showed the superior quality of the epitaxial GeSn layers.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] Composition of Sn for this transition is stated over a range, since the bowing parameter of Ge 1Ày Sn y in the computation of energy bandgap varies between experimental and first-principles calculations. 21 Additionally, Ge 1Ày Sn y material has inherent advantages, such as: (i) increased direct band transitions of the carriers between conduction and valence bands, improving optical absorption to provide high photodetector responsivities; [22][23][24] (ii) lower effective mass (m eff ) of carriers in the G-valley than L-valley enhances mobility -thereby boosting the ON-current in a low power transistor; 25,26 (iii) compatibility with Si CMOS technology; [27][28][29][30] (iv) high carrier lifetime due to reduced surface roughness 31 by mitigating surface states induced recombination. Hence, a virtually defect-free lattice matched GeSn/InAlAs (or InGaAs) heterostructure is necessary to make better use of Ge 1Ày Sn y material in photonic integrated circuits (PICs) and optoelectronic applications.…”

Radiative Carrier Lifetime in Ge$_{1-x}$Sn$_x$ Mid-Infrared Emitters

“…For instance, timeresolved photoluminescence (PL) can hardly be applied to investigate materials at emission wavelengths in the mid-infrared range as high-speed detectors covering this range are not broadly available. Thus, the very few reported time-resolved studies concern Ge 1−x Sn x emitting below 2.3 µm corresponding to a relatively low Sn content * oussama.moutanabbir@polymtl.ca and/or highly compressively strained materials [19][20][21].…”

“…Additionally, by investigating spin-dependent optical transitions leveraging the Hanle effect under steady-state excitation, systematic studies combining modeling and magneto-PL analysis of pseudomorphic layers at a Sn content below 10% reported a radiative lifetime in the 0.5-2.5 ns range at 10 K [20]. However, significantly higher carrier lifetimes reaching 450 ns were recently reported for Ge 1−x Sn x (x < 0.06) grown on InAlAs buffer layers as measured by contactless microwave photoconductive decay [21]. This scarcity of studies on carrier dynamics in narrow bandgap Ge 1−x Sn x semiconductors limits the understanding of their fundamental behavior and burdens the development of accurate and predictive models for Ge 1−x Sn x -based mid-infrared optoelectronic devices.…”