Optically pumped low-threshold microdisk lasers on a GeSn-on-insulator substrate with reduced defect density

Abstract

Despite the recent success of GeSn infrared lasers, the high lasing threshold currently limits their integration into practical applications. While structural defects in epitaxial GeSn layers have been identified as one of the major bottlenecks towards low-threshold GeSn lasers, the effect of defects on the lasing threshold has not been well studied yet. Herein, we experimentally demonstrate that the reduced defect density in a GeSn-on-insulator substrate improves the lasing threshold significantly. We first present a method of obtaining high-quality GeSn-on-insulator layers using low-temperature direct bonding and chemical–mechanical polishing. Low-temperature photoluminescence measurements reveal that the reduced defect density in GeSn-on-insulator leads to enhanced spontaneous emission and a reduced lasing threshold by ∼ 10 times and ∼ 6 times, respectively. Our result presents a new path towards pushing the performance of GeSn lasers to the limit.

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

“…Indeed, with the thermal energy of about 0.34 meV at 4 K, one should expect a noticeable increase in the spontaneous emission intensity R sp . Moreover, using equation (10), the steady-state radiative carrier lifetime τ rad was extracted (Fig. 3(a)) and shown to decrease from 3.52 to 1.89 ns in the range of power density used in this study.…”

“…Ge 1−x Sn x alloys constitute an emerging class of group IV semiconductors providing a tunable narrow bandgap, which has been highly attractive to implement scalable, silicon-compatible mid-infrared photonic and optoelectronic devices [1]. This potential becomes increasingly significant with the recent progress in nonequilibrium growth processes enabling high Sn content Ge 1−x Sn x layers and heterostructures leading to the demonstration of a variety of monolithic mid-infrared emitters and detectors [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Notwithstanding the recent developments in device engineering, the impact of structural characteristics on the basic behavior of charge carriers is yet to be fully understood.…”

Impact of strain engineering and Sn content on GeSn heterostructured nanomaterials for nanoelectronics and photonic devices

“…Then, the microdisk was made by E-lithography, followed by dry etching. They obtained 2330 nm lasing line at a lower threshold pumping density of 17 kW cm −2 at 4 K. 141 The following table (Table 4) summarizes the threshold value of different wavelengths of the lasing line with different Sn contents affected by the carrier confinement and the relaxation of the GeSn layers, thus reducing their dislocation to enhance GeSn emission.…”

Strong extended SWIR cavity resonances in a single GeSn nanowire

“…Recently, CMOS-compatible group-IV materials such as Ge and GeSn have attracted much attention as a gain medium for on-chip lasers operating at wavelengths deep in the infrared relevant to free-space communication and sensing applications [10][11][12][13][14][15] . Particularly, group-IV bottom-up nanowires have the potential to produce the smallest, CMOS-compatible on-chip light sources, thus motivating many researchers to grow high-quality Ge and GeSn [16][17][18][19][20][21][22][23][24][25] .…”