Light absorption enhancement in Ge nanomembrane and its optoelectronic application

Abstract

In this study, the light absorption property of Ge nanomembrane (Ge NM), which incorporates hydrogen (H), in near-infrared (NIR) wavelength range was analyzed. Due to the presence of a large amount of structural defects, the light absorption coefficient of the Ge layer becomes much higher (10 times) than that of bulk Ge in the wavelength range of 1000 ~1600 nm. Increased light absorption was further measured from released Ge NM that has H incorporation in comparison to that of bulk Ge, proving the enhanced light absorption coefficient of H incorporated Ge. Finally, metal-semiconductor-metal (MSM) photodetectors were demonstrated using the H incorporated Ge on GeOI.

Low dimensional freestanding semiconductors for flexible optoelectronics: materials, synthesis, process, and applications

“…The abovementioned semiconductor NMs have been actively studied to enhance the performance of various electronic/optoelectronic devices such as reflectors [54], photodetectors [63][64][65], light-emitting diodes [66][67][68], and transistors [55,69]. They are either becoming the main body of the devices or adding additional functionalities as a key enabler for the enhanced performance.…”

Strain-free GeSn nanomembranes enabled by transfer-printing techniques for advanced optoelectronic applications

“…In this paper, we present a new strategy to achieve strain-free GeSn alloys via a transfer-printing of nanomembranes (NMs). Single-crystalline semiconductor NMs are transferrable free-standing thin films with unique advantages such as excellent mechanical flexibility and material quality (e.g., high mobility and light absorption) [33][34][35][36][37][38]. By transferprinting the GeSn NMs and removing the Ge buffer layer, the compressive strain that was initially stored in the GeSn was successfully removed.…”

“…The process began with the epitaxial growth of the 370-nm GeSn alloy using MBE (Figure 1(a-i)). Standard photolithography and dry etching were used to pattern the NMs with an array of etching holes, followed by a hydrofluoric (HF) undercut process (Figure 2(a-ii)) [33]. Then, the released NMs (i.e., GeSn/Ge/Si) were flip transfer-printed on an adhesive layer (SU-8 2002) with a thickness of ~2 µm, then coated on the 120-µm polyethylene terephthalate (PET) (Figure 2(a-iii)).…”

“…To further confirm the bandgap reduction by the strain relaxation effect, we analyzed the strained bandgap energy using deformation potential theory [33,34] (see Supporting Information). The direct bandgap of pseudomorphic Ge0.0967Sn0.033 on the Ge buffer and the strain-free Ge0.0967Sn0.033 NMs are calculated to be 708 and 683 meV, respectively, which is in good agreement with the experimental results.…”

Modulation of light absorption in flexible GeSn metal–semiconductor–metal photodetectors by mechanical bending

“…2 Among various flexible materials, semiconductor nanomembranes (NMs) are especially attractive in high performance flexible photonic applications because of the great advantages including excellent material properties (e.g., fast carrier mobility and high absorption capability) and strong bendability. Wellknown examples of such semiconductor NMs are group IV (e.g., Si and Ge), 3,4 III-V (e.g., GaAs), 5 and wide bandgap (e.g., GaN and 4H-SiC) materials. 6 Group IV NMs have been widely explored as active layers for enhanced light absorption and emission properties in flexible Si photonics due to the mature complementary metal-oxide-semiconductor (CMOS) process technology.…”