Material Gain Analysis of GeSn/SiGeSn Quantum Wells for Mid-Infrared Si-Based Light Sources Based on Many-Body Theory

Abstract

Abstract-Material gain of GeSn/SiGeSn quantum wells, which can be grown on Si substrate by using a buffer layer, is analyzed based on microscopic many-body theory (MBT) for mid-infrared light sources based on Si photonics. MBT can take into account a gain spectrum broadening associated with scattering phenomena, such as Coulomb scattering, based on quantum field theory, and does not need any artificial fitting parameters, such as a relaxation time, used in conventional analysis. Not only Γ-but also carrier distributions in L-points are considered for the gain analysis. By using MBT, the quantum well structures maximizing the material gain and the differential gain at the threshold are investigated in terms of the well thickness, the strain, and the energy difference of quantum states between Γ-and L-points.Index Terms -Mid-infrared photonics, Si photonics, GeSn quantum wells, and many-body theory.

GeSn/SiGeSn Multiple-Quantum-Well Electroabsorption Modulator With Taper Coupler for Mid-Infrared Ge-on-Si Platform

“…Deep well leads to stronger electron confinement and steep extinction characteristics [17]. The material parameters, such as lattice constant and bandgap, used in this paper are the same as [16] and [17]. Figure 2 shows the calculated absorption spectra (TE polarization) of the GeSn/SiGeSn QW by MBT for various values of applied electric fields.…”

“…In this paper, we propose taper coupler EAM composed of GeSn/SiGeSn MQW on Ge-on-Si platform for mid-infrared (2 μm) integrated optical active devices. GeSn/SiGeSn QW design for 2-m band QCSE is done for the first time and the epitaxial design is performed by calculating the absorption spectra of GeSn/SiGeSn MQW using many-body theory developed for group IV materials [16,17] to investigate the extinction characteristics of GeSn MQW waveguides. Two types of taper couplers are considered for connecting Ge-rib waveguide and GeSn-MQW-highmesa waveguide efficiently and comprehensive comparison of two structures, ATC type EAM and RTC type EAM, is done.…”

Quantum-Confined Stark Effect Analysis of GeSn/SiGeSn Quantum Wells for Mid-Infrared Si-Based Electroabsorption Devices Based on Many-Body Theory

“…The well is Ge(Sn) and the barrier is SiGe(Sn) and their thickness and strain are L w and ε w , L B and ε B . The band structure of QWs is calculated by k•p theory [8,14]. To treat QCSE, the effect of applied electric field, F, is taken into account.…”

“…The final term in (1) is the scattering contribution and derived from the commutation of Hamiltonian and the operator for p kt . The detailed formulation and numerical treatment can be found in [8,12,18]. By discretizing (1) for the steady-state condition (the left-hand side of (1) is zero), we obtain a simultaneous equation and by solving it, the microscopic polarization is calculated for discretized k t and a macroscopic polarization, P macro , is obtained by summing the microscopic polarization over all the states.…”

Germanium-tin alloys: applications for optoelectronics in mid-infrared spectra

“…Furthermore, the thermal stability of GeSn film caused by high Sn content becomes an obstacle to device fabrication [20][21][22][23][24] . By inducing a tensile strain into GeSn alloys, the Sn composition can be reduced to achieve direct bandgap compared with the relaxed one 2,25,26 , benefiting their light emission efficiency 27,28 . Therefore, silicon nitride (SiN x ) films are used as an external stressor to induce tensile or compressive strain into semiconductor [29][30][31][32] , which poses a strategy to improve the optical performance of the strained GeSn-based structures.…”