Optical fiber-enhanced photoreflectance and contactless electroreflectance measurements of van der Waals crystals and III-V semiconductor materials

• Traditional PR and CER setups enhanced by the integration of optical fibers. • Optical fibers allow the scanning of sample properties with spatial control. • Significantly stronger signal amplitudes observed with fiber-based setups. • Sapphire dielectric boosts CER signal and protects sample from electrical breakdown. • Decoupling of sample from setup enabled by freely positioned optical fiber. Among many different applications, optical fibers have not been widely utilized in fundamental optical studies of semiconductors. Their integration into different scientific domains typically leads to the miniaturization and simplification of measurement systems. Here, the optical fiber is integrated into a modulation spectroscopy setup, allowing for the optical characterization of semiconductor materials including van der Waals crystals. Investigating fibers with different core diameters in photoreflectance experiments revealed distinct advantages: fibers with smaller cores are suitable for scanning samples with micrometer spatial resolution, while larger cores facilitate maintaining a greater distance from the sample. In contactless electroreflectance measurements, using fibers enhances the signal and allows for precise electrode positioning, significantly reducing the risk of electrical breakdown. Most importantly, integrating fiber allowed for decoupling the measurement zone from the experimental setup. This pioneering approach not only refines optical spectroscopy methodologies but also optimizes experimental conditions while prioritizing safety and integrity.