Si based GeSn photoconductors with a 1.63 A/W peak responsivity and a 2.4 μm long-wavelength cutoff

Abstract

Thin-film Ge0.9Sn0.1 structures were grown by reduced-pressure chemical vapor deposition and were fabricated into photoconductors on Si substrates using a CMOS-compatible process. The temperature-dependent responsivity and specific detectivity (D*) were measured from 300 K down to 77 K. The peak responsivity of 1.63 A/W measured at 1.55 μm and 77 K indicates an enhanced responsivity due to photoconductive gain. The measured spectral response of these devices extends to 2.4 μm at 300 K, and to 2.2 μm at 77 K. From analysis of the carrier drift and photoconductive gain measurements, we have estimated the carrier lifetime of this Ge0.9Sn0.1 thin film. The longest measured effective carrier lifetime of 1.0 × 10−6 s was observed at 77 K.

Dislocation density and strain-relaxation in Ge 1−x Sn x layers grown on Ge/Si (0 0 1) by low-temperature molecular beam epitaxy

“…This approach has been shown in previous works to yield very reliable estimates of dislocation density for GaN [18][19][20] and SiGe [21][22][23] epitaxial layers. Unlike in the more-widely-used Dunn and Koch method [35] (or the Williamson-Hall method [36]), which relies solely upon the FWHM value of a Gaussian distribution of the diffracted intensity, to determine the TDD by the Kaganer approach, the -rocking curves are fitted by [16] ( ) = ∫ (− 2 + ) cos( ) + ∞ 0 … … … (5) where and are the integrated peak intensity and the background intensity, respectively. Numerical fit of Equation (5) to the rocking curves of the different samples are shown (by the red traces) in Figs.…”

“…Moreover, Ge1-xSnx has been demonstrated to undergo an indirect to direct band gap transition for Sn-content of ~ 7 % and above (when fully relaxed) [2,3]. Intensive research efforts over the last five years have thus led to the fabrication of Ge1-xSnx based photoconductors [4,5], photodiodes [6,7,8], and light emitting diodes [3,9], and also to the first demonstration of optically pumped lasing in 2015 [10]. The spectral response of Ge1-xSnx based photodetectors now extends all the way up to 2.4 m [11].…”

Towards low-loss waveguides in SOI and Ge-on-SOI for mid-IR sensing

“…Similarly, a proposed monolithically integrated Ge-on-SOI mid-IR sensor benefits from low-loss propagation provided by Ge core and the optical absorption in epitaxially grown GeSn layer at the top, as shown in figure 8. GeSn with 9%-10% Sn concentration is able to achieve photodetection in 2.2-2.4 μm wavelengths [19,20]. The large refractive index of GeSn provides vertical coupling of light from waveguide core into the active layer.…”

“…Additionally, germanium-tin (GeSn), an alloy of Ge, has gained significant popularity as on-chip mid-IR source in Ge-on-Si [18]. GeSn has also been widely reported for photodetection, and a relatively higher concentration of 9%-10% Sn has been used to demonstrate photodetector and photoconductor for 2.2-2.4 μm wavelengths in [19] and [20], respectively. A waveguide GeSn photodetector has been reported in [21].…”

Разрывы валентной зоны в напряженных слоях SiGeSn/Si с различным содержанием олова

“…Кроме того, поскольку α-Sn является полупроводником с инвертиро-ванной зонной структурой, вариация содержания олова в сплавах дает значительно больший диапазон ширин запрещенной зоны, которые могут быть использованы в приборах на основе твердых растворов SiGeSn, по сравнению с приборами на SiGe. На данный момент имеется множество работ экспериментального характе-ра, посвященных формированию тройных соединений SiGeSn [10][11][12][13], измерению оптических свойств этих полупроводников [13][14][15][16][17] и изготовлению отдельных приборных структур с использованием рассматриваемых твердых растворов [18][19][20]. Существуют теоретические работы, посвященные моделированию зонной структуры как напряженных, так и релаксированных [5,6] тройных соединений.…”