Reduced Lasing Thresholds in GeSn Microdisk Cavities with Defect Management of the Optically Active Region

Abstract

GeSn alloys are nowadays considered as the most promising materials to build Group IV laser sources on silicon (Si) in a full complementary metal oxide semiconductorcompatible approach. Recent GeSn laser developments rely on increasing the band structure directness, by increasing the Sn content in thick GeSn layers grown on germanium (Ge) virtual substrates (VS) on Si. These lasers nonetheless suffer from a lack 1 of defect management and from high threshold densities. In this work we examine the lasing characteristics of GeSn alloys with Sn contents ranging from 7 % to 10.5 %. The GeSn layers were patterned into suspended microdisk cavities with different diameters in the 4-8 µm range. We evidence direct band gap in GeSn with 7 % of Sn and lasing at 2-2.3 µm wavelength under optical injection with reproducible lasing thresholds around 10 kW cm −2 , lower by one order of magnitude as compared to the literature. These results were obtained after the removal of the dense array of misfit dislocations in the active region of the GeSn microdisk cavities. The results offer new perspectives for future designs of GeSn-based laser sources.

Review of Si-Based GeSn CVD Growth and Optoelectronic Applications

“…Encouraged by this major technical breakthrough, researchers used the injection methods such as optical injection with a Ge laser to check the GeSn waveguide, and lasing behavior was clearly observed at a low temperature in 2015 [ 70 ]. Following this breakthrough, several types of GeSn lasers [ 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 ] were demonstrated, though they still suffer from the problems of low-temperature operation and high lasing thresholds. To overcome these difficulties, several methods have been proposed to improve performance, such as greater Sn incorporation into Ge [ 73 , 75 , 76 ], the use of SiGeSn/GeSn/SiGeSn heterostructures or SiGeSn/GeSn/SiGeSn MQWs as the gain medium [ 83 , 84 , 85 , 86 ], a modulation doping scheme in SiGeSn/GeSn/SiGeSn MQWs [ 87 ], defect management [ 80 ], and thermal management [ 81 , 82 ].…”

Synthesis of ZnO sol–gel thin-films CMOS-Compatible

“…In some manufacturing technologies, this has led to alternative hybrid technology (also called heterogeneous integration), where the materials or components are on separate chips, and then combined in a single packaging. 64,65 However, the thin lm high-temperature growth prevents direct growth on CMOS chips, and the transfer process adds extra cost to the nal product. The post-annealing treatment of ZnO sol-gel thin-lms can vary between 250 C to 900 C based on the substrates used.…”

Screening of spherical moulds manufactured isotropically in plasma etching conditions

“…The undercut is sometimes desirable and even necessary. [42] For isotropic processes, the etch rate is uniform in all directions (i.e., the etch depth is equal to the undercut), thus forming a spherical profile. Hence, SEM images of samples were taken by cleaving the silicon wafers through the centre of a row of etched cavities and examining the cavities' profile, as demonstrated in Figure 1.…”