Fabrication and optical characterization of V-shaped micro/nano-grooves on indium phosphide surface through double cell electrochemical etching

A versatile and simple method of fabricating micro and nano-grooves on the indium phosphide (InP) semiconductor surface using a double-cell electrochemical etching process is presented in this work. The formation mechanism of the groove structures is thoroughly investigated as a function of different etching parameters, including varying acid concentration, current density, and etching time. The surface morphologies and chemical compositions of the grooves are analyzed using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). It has been observed that electrochemical etching using HCl-based etchants leads to the spontaneous formation of micro and nano-sized grooves on certain side facets of patterned structures, depending on the etching parameters. At high acid concentration, micro-grooves with a lateral length of 980 nm are formed by applying a low current density of 30 mA/cm2 for 6 min. On the other hand, it is revealed that the applied current density needs to be increased to 50 mA/cm2 to obtain a regular grooved InP surface at low acid concentration. Tailoring the etching parameters results in much smaller structures with novel nano-sized features. The impact of morphology on the optical and carrier recombination properties is comprehensively investigated using a steady state photoluminescence (PL) spectrometer and a time-resolved fluorescence lifetime imaging microscope (FLIM). At room temperature, the nano-grooved InP surface exhibits a well-defined, strong emission peak at 920 nm and a carrier recombination lifetime of 6.06 ns. Patterning semiconductor micro/nanostructures with precisely controlled geometries offers a promising opportunity to enhance the performance of optoelectronic devices.