Saw-Tooth Heat-Cycling Nitridation of Metallic Cu Yields First Photoactive p-Cu₃N for PEC Applications

Abstract

Copper nitride (Cu 3 N)-based binary and ternary semiconductors have the potential to significantly impact photovoltaic and photoelectrochemical applications due to their ideal and tunable band gaps and good charge carrier mobility. Yet their development has been hindered due to thermal instability, which limits process temperatures to below 200 °C, and thus the persistence of intrinsic defects has made the demonstration of photoactive Cu 3 N elusive. Here, by understanding the thermal nitridation characteristics of metallic Cu in a NH 3 /O 2 atmosphere by in situ X-ray diffraction (XRD), we developed a saw-tooth heat-cycling method that improves crystallinity, grain size, and morphology of Cu 3 N, resulting in the first demonstration of photoactive material to date. Furthermore, this processing method stabilizes Cu 3 N at temperatures as high as 550 °C, allowing for improved process parameterization. This study introduces a strategy for economically fabricated Cu 3 N photocathodes and paves the way for their future integration as light absorbers in solar energy harvesting applications.

Enhanced Electrical Properties of Copper Nitride Films Deposited via High Power Impulse Magnetron Sputtering

“…At room temperature, Cu 3 N with a lattice constant lower than 38 Å possesses huge electrical resistivity [10]. Thanks to abundant resource availability, cheap manufacturing costs, non-toxicity, low deposition temperature and also being highly adaptable to several substrates [12,13], Cu 3 N can be applied in numerous fields such as photodetectors [14], optical storage memory [15], integrated circuits [16], tunnel junctions [17], resistive random-access memory [18], solar energy conversion [19], photovoltaic absorber [20], diode rectifier [21], lithium-ion batteries [22], etc.…”

Effect of Argon on the Properties of Copper Nitride Fabricated by Magnetron Sputtering for the Next Generation of Solar Absorbers

“…In the case of Cu3N, the reported Eg values suggest that this material can be a potential solar absorber for the next generation of photovoltaic devices [5]. In this sense, Cu3N has garnered interest in different application fields, such as optical storage media [6], tunnel junctions [7], solar energy conversion [8], and photovoltaics [9], due to its unique crystal structure and physicochemical properties.…”

“…In addition, thanks to its good electrical properties and the ease with which it can be fabricated, the use of this material as a solar absorber could help avoid the hightemperature steps involved in the fabrication of solar-grade silicon. Furthermore, thanks to bipolar doping [17], this material can be profitably used in rectifying heterojunctions [18][19][20] as well as homojunctions [8][9][10][11][12][13][14][15][16][17][18][19][20][21], and in solar cells [8,17,22].…”