The effect of passivation to etching duration ratio on bipolar electrochemical etching of porous layer stacks in germanium

Schreiber, Waldemar; Liu, Tingzhu; Janz, S.

doi:10.1016/j.jpcs.2023.111265

Cited by 6 publications

(1 citation statement)

References 21 publications

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“…Among them, the porosification lift-off technique has recently received significant attention and development thanks to its potentially high-throughput and cost-effective process [20,25]. This approach involves the formation of a uniform and tunable porous Ge (PGe) layer [43] using electrochemical etching [44][45][46][47], followed by the deposition of a Ge membrane on top of it. The membrane can then be detached from the parent substrate through the weak nanostructured interface, forming a thin Ge FSM.…”

Section: Introductionmentioning

confidence: 99%

Sustainable Production of Ultrathin Ge Freestanding Membranes

Hanuš,

Ilahi,

Cho

et al. 2024

Sustainability

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Germanium (Ge) is a critical material for applications in space solar cells, integrated photonics, infrared imaging, sensing, and photodetectors. However, the corresponding cost and limited availability hinder its potential for widespread applications. However, using Ge freestanding membranes (FSMs) allows for a significant reduction in the material consumption during device fabrication while offering additional advantages such as lightweight and flexible form factor for novel applications. In this work, we present the Ge FSM production process involving sequential porous Ge (PGe) structure formation, Ge membrane epitaxial growth, detachment, substrate cleaning, and subsequent reuse. This process enables the fabrication of multiple high-quality monocrystalline Ge FSMs from the same substrate through efficient substrate reuse at a 100 mm wafer scale by a simple and low-cost chemical cleaning process. A uniform, high-quality PGe layer is produced on the entire recovered substrate. By circumventing the use of conventional high-cost chemical–mechanical polishing or even substantial chemical wet-etching, and by using an optimized PGe structure with reduced thickness, the developed process allows for both cost and an environmental impact reduction in Ge FSMs production, lowering the amount of Ge used per membrane fabrication. Moreover, this process employs large-scale compatible techniques paving the way for the sustainable production of group IV FSMs for next-generation flexible optoelectronics.

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