We here report a method for fabricating a heat-resistant alloy based on NiW electroplating and silicon lost-molding processes. A periodic micropattern was fabricated on a silicon mold by electronbeam lithography and deep reactive-ion etching. A heat-resistive NiW alloy film with a thickness of 2.1 m was subsequently electroplated onto an Au seed layer deposited on the silicon mold, following which the silicon mold was finally etched, and a free-standing NiW alloy film was released. The NiW film was characterized by energy-dispersive X-ray spectrometry and Fourier transform infrared spectrophotometer. The film contained 24.6 at% tungsten, and its melting point was estimated to be 1675 C. Modification of the film's spectral reflectivity was confirmed, and an emission peak at 1.4 m was observed; This emission wavelength agrees well with the absorption band of a conventional infrared photovoltaic cell of Ge. Thermophotovoltaic power generation was demonstrated using a Ge photodiode and Joule heating of the micropatterned NiW film, and a radiation efficiency of 9 13 × 10 −6 was achieved.

The material properties of electroplated NiW alloys with potential for use as emitters in thermionic energy converters were investigated. NiW alloy films with W content ranging from 11 to 25 at% were electroplated and the material properties of the alloy films including their surface morphologies, and crystallinities, were determined. The work functions of the NiW films were also evaluated using photoemission yield spectroscopy and were found to be independent of the W content. In addition, heat treatment up to 700°C in a vacuum chamber of a NiW film with 21.4 at% W content decreased the electron yield with increasing its work function.

A process for the simultaneous fabrication of microcavity structures on both sides of a film was proposed and demonstrated to develop a free-standing-type integrated absorber–emitter for use in solar thermophotovoltaic power generation systems. The absorber–emitter-integrated film comprised a heat-resistant Ni–W alloy deposited by electroplating. A two-step silicon mould was fabricated using deep reactive-ion etching and electron beam lithography. Cavity arrays with different unit sizes were successfully fabricated on both sides of the film; these arrays are suitable for use as a solar spectrum absorber and an infrared-selective emitter. Their emissivity spectra were characterised through UV–vis–NIR and Fourier transform infrared spectroscopy.