Tensile-strained germanium-on-insulator substrate fabrication for silicon-compatible optoelectronics

Abstract

We present a method to fabricate tensile-strained germanium-oninsulator (GOI) substrates using heteroepitaxy and layer transfer techniques. The motivation is to obtain a high-quality wafer-scale GOI platform suitable for silicon-compatible optoelectronic device fabrication. Crystal quality is assessed using X-Ray Diffraction (XRD) and Transmission Electron Microscopy. A biaxial tensile film strain of 0.16% is verified by XRD. Suitability for device manufacturing is demonstrated through fabrication and characterization of metal-semiconductor-metal photodetectors that exhibit photoresponse beyond 1.55 μm. The substrate fabrication process is compatible with complementary metal-oxidesemiconductor manufacturing and represents a potential route to wafer-scale integration of silicon-compatible optoelectronics.

Strained germanium thin film membrane on silicon substrate for optoelectronics

“…Other approaches include highly strained nanocrystal structures that show an increase by 2 orders of magnitude in photoluminescence as compared to bulk Ge [15]. Germainum-On-Insulator (GOI) substrate using layer transfer techniques presented 0.16% tensile strain for Ge optoelectronics [16]. GeSn is theoretically predicted to have a direct bandgap at an Sn concentration of 9% and the epitaxial growth of high-Sn concentration GeSn alloys is also experimentally demonstrated to show the bandgap reduction in the Γ valley [17,18].…”

Observation of improved minority carrier lifetimes in high-quality Ge-on-insulator using time-resolved photoluminescence

“…Recently, several researchers demonstrated techniques to fabricate a Ge-on-insulator (GOI) substrate by transferring an epitaxial Ge film grown on Si to a handle wafer [12][13][14]. The defective Ge/Si interface of a Ge-on-Si carrier wafer becomes the top interface of a GOI substrate after the layer transfer.…”

“…The defective Ge/Si interface of a Ge-on-Si carrier wafer becomes the top interface of a GOI substrate after the layer transfer. And by polishing away the defective top interface, a relatively defect-free Ge layer was obtained, and the film's structural properties were assessed by transmission electron microscopy (TEM) and x-ray diffraction (XRD) studies [12]. However, studies on minority carrier lifetimes of the high-quality Ge film on insulator have been completely lacking, although improving the film's quality is primarily advantageous for reducing nonradiative recombination rate and thereby improving Ge's minority carrier lifetime.…”

Suspended low-loss germanium waveguides for the longwave-infrared

“…The wafers were fabricated using Ge-on-SOI with a 1 µm Ge layer grown by RPCVD on SOI in which the Si layer was thinned from 220 nm down to 60 nm. This platform was chosen over the GOI due to the fact that current methods for fabricating GOI films require tight process control and limit the range of thicknesses that can be obtained [33]. Moreover, bonded GOI wafers are not commercially available.…”