Theoretical Investigation of Strain-Adjustable Ge_0.92Sn_0.08 Light-Emitting Diodes With Giant Magnetostrictive Stressor for Short-Wave Infrared Light Source

Abstract

A new idea was provided by the group-IV GeSn alloys for short-wave infrared light source compatible with CMOS due to the low cost integrated on the Si platform and can be transformed into direct bandgap alloy. More than 7.1% Sn content or strain engineering is used to achieve the direct bandgap GeSn semiconductors and enhance the luminous efficiency of GeSn light-emitting devices. We theoretically investigate a strainadjustable GeSn light-emitting diode with the giant magnetostrictive stressor. A 0 ~ 0.11% adjustable uniaxial tensile strain is introduced into Ge0.92Sn0.08 LED by adjusting the external magnetic field. A continuously adjustable bandgap from 0.543 eV to 0.475 eV of the Ge0.92Sn0.08 alloy is achieved in the magnetic field intensity range of 0 ~ 240 kA/m, and the spontaneous emission rate of the strained LED is enhanced about 3.63 times compared with the relaxed device. Besides, an adjustable range of luminous peak is achieved from 2.18 μm to 2.46 μm, which can promote the application of GeSn light source for magnetic field detection and photo-communication in short-wave infrared.

Design of tensile-strained GeSn/SiGeSn structure for low threshold mid-infrared laser application

“…The latticematched Ge 1−x Sn x /Si 1−y−z Ge y Sn z heterostructure and the Itype band alignment at Γ point are achieved by tuning x, y and z [35][36][37][38]. The metal electrodes are prepared by metal contact deposition with a lift-off process [9,39], where the metal contact is an Ohmic Contact and the top metal electrode can be formed through the contact holes of Si 3 N 4 . The Si 3 N 4 stress liner is deposited by plasma enhanced chemical vapor deposition [40,41], and the thickness (d) of Si 3 N 4 stress liner is estimated by the strain simulation results.…”

“…Assuming the wavelength of the spontaneous emission peaks is the laser λ, which can be achieved by [39,50]. The λ of relaxed and tensile strained Ge 0.90 Sn 0.10 /Si 0.315 Ge 0.499 Sn 0.186 heterostructure lasers are 2.68 and 3.44 µm, respectively [39]. The optical gain is equal to Γ g, where Γ is the optical confinement factor.…”