Nanoindentation techniques in the measurement of mechanical properties of InP-based free-standing MEMS structures

Abstract

Recent advances in high-speed networks have made micro-electro-mechanical systems (MEMS) find some niche applications in tunable optical devices. Indium phosphide (InP)-based MEMS have an inherent advantage of being direct band gap as compared to silicon and can thus be used in MEMS structures with light emission/detection capability. In this paper, we report an in-depth study using nanoindentation to determine the mechanical properties of InP free-standing structures that could be incorporated in optical MEMS. The fabrication process for InP-based cantilever beams and membranes is also reported. Young's modulus of the material is determined from both loading and unloading of the InP cantilever beam through a bending test. We also discuss the deformation behaviour of the InP cantilever beam. Indentation on an InP substrate was conducted using a spherical indenter of known radius, in addition to the conventional Berkovich tip. The results were compared with ideal analytical methods. Experiments were also carried out to determine Young's modulus and hardness using continuous stiffness mode (CSM) tests. In addition, as a benchmark, experiments on silicon and sapphire substrates are also discussed. The results show good agreement in the mechanical properties obtained through different experiments.

Effect of hygrothermal ageing on morphology and indentation modulus of injection moulded nylon 6/organoclay nanocomposites

“…Hence, one effective way to overcome this difficulty is to test very small specimens. Nanoindentation is an emerging technique which has been widely used to determine the mechanical properties of small components [13,14]. In the present investigation, this type of mechanical test not only saved time in regard to water conditioning of the samples, but it also enabled the study of the effect of hygrothermal ageing in different regions of the injection moulded specimens.…”

Fabrication challenges for indium phosphide microsystems

“…By varying membrane and suspension dimensions, a range of internal mirror stresses from 0.24 to 0.08 GPa were measured, highlighting the importance of suspension and device design. Based on these studies, they designed four different optimized suspension designs for a suspended Fabry-Perot interferometer filter [13,77].…”

“…In recent years, microelectromechanical systems (MEMS) using InP-based materials have been investigated to augment these optical networks [7]. A number of examples have been reported in literature of optical modulators, demultiplexers [8][9][10][11][12][13], and couplers [14,15] all designed in III-V materials to facilitate monolithic integration of these optical components with photodetectors and sources. To our knowledge, there have not been any examples which have demonstrated full monolithic integration of these MEMS components with their active optical elements (sources and detectors) for a variety of reasons.…”

Localized Deformation and Fracture Behaviors in InP Single Crystals by Indentation

“…Owing to its high electron velocity and the direct bandgap (~1.35 eV), zincblende-structured indium phosphide (InP) has been regarded as one of the most important III–V semiconductors. Currently, applications based on InP have been realized in a wide variety of electronic and photonic devices and systems, such as high-power and high-frequency electronics, solar cells, photodiodes, photodetectors, light-emitting diodes (LEDs), field effect transistors (FETs), and micro-electro-mechanical systems (MEMS) [18,19,20]. From an application point of view, in addition to its optoelectronic properties, a full understanding of the mechanical properties of InP is equally essential in order to widen its applications and manipulate the performance of devices.…”