UHV-CVD growth of high quality GeSn using SnCl₄: from material growth development to prototype devices

Abstract

The persistent interest of the epitaxy of group IV alloy GeSn is mainly driven by the demand of efficient light source that could be monolithically integrated on Si for mid-infrared Si photonics. For chemical vapor deposition of GeSn, the exploration of parameter window is difficult from the beginning due to its non-equilibrium growth condition. In this work, we demonstrated the effective pathway to achieve the high quality GeSn with high Sn incorporation. The GeSn films were grown on Ge-buffered Si via ultra-high vacuum chemical vapor deposition using GeH4 and SnCl4 as precursor gasses. The influence of both SnCl4 flow fraction and growth temperature on the Sn incorporation and material quality were investigated. The key to achieve effective Sn incorporation and high material quality is to explore the proper parameter match between SnCl4 supply and growth temperature, which is also called optimized growth regime. The Sn precipitation is significantly suppressed in optimized growth regime, leading to more Sn incorporation into Ge and enhanced material quality. The prototype GeSn photoconductors were fabricated with typical samples, showing the promising devices applications towards mid-infrared optoelectronics.

Decreasing CCT deviation of white light emitting diodes by employing SiO2 nanoparticles

“…In lighting configuration with SiO2 particles, the SiO2 was doped at the ratio of 1% to 3% of the phosphor material in the configuration. As a result, the refractive indices of the phosphor material in each layer were 1.428 and 1.445 [20]. The TFCalc32 simulation was employed as a tool to analyze the impacts of various refractive index in the layers.…”

Facile synthesis of Ge1−xSnx nanowires

“…Ge 1−x Sn x has attracted much research interest as an exciting material with potential applications in nextgeneration rechargeable lithium-ion battery anodes and optoelectronic devices, due to their high carrier mobilities [1][2][3] and a direct band gap which can be tuned by varying the tin concentration [4][5][6][7][8][9][10][11][12]. Additionally, cubic Ge 1−x Sn x allows the lattice dimensions to be tuned over a wide range, which is beneficial when used as a buffer layer to reduce strain arising from lattice mismatch between III-V or II-VI compounds with silicon or germanium substrates [13][14][15].…”

“…The synthesis of Ge 1−x Sn x is challenging due to the low solubility of tin in germanium (<1%) [16], large lattice mismatch (∼14%) and a tendency of metallic tin to segregate from germanium [17,18]. Ge 1−x Sn x alloys are commonly fabricated using ion implantation, laser melting [4,5,19], molecular beam epitaxy (MBE) [7], and chemical-vapor deposition(CVD) approaches [6,[20][21][22]. Apart from these thin film based preparations, there are limited reports of the synthesis of anisotropic Ge 1−x Sn x nanostructures by top-down and bottom-up approaches [12,[23][24][25][26][27][28].…”

Study of GeSn Mid-infrared Photodetectors for High Frequency Applications

“…Recently, Silicon-germanium-tin (SiGeSn) and Germaniumtin (GeSn) techniques have drawn much attention due to the success of developing all-group-IV alloy with outstanding material properties including (i) independent tuning of the lattice constant and bandgap by simultaneously varying the compositions of Si, Ge, and Sn (Jenkins and Dow, 1987); (ii) true direct-bandgap material (Zhou et al, 2019); (iii) wavelength coverage up to 12 µm (Du et al, 2016); and (iv) a low material growth temperature fully compatible with CMOS processes (Grant et al, 2019). The advantages of a SiGeSn approach are (i) compatibility with the proven high-performance Silicon on Insulator (SOI) passive and Electro-optic (EO) components, and (ii) enhanced dynamic range as two-photon absorption at 1.55 µm in Si under high laser power operation is effectively suppressed by shifting the operating wavelength to 2 µm and beyond (Cao et al, 2018).…”