Compound characterization data

Cu|ZnO junction
Current–voltage, room-temperature Schottky barrier	0.40–0.50 eV
Current–voltage, room-temperature diode ideality factor	1.6–1.8
Current–voltage, room-temperature reverse bias	Current magnitude increased linearly with applied reverse-bias voltage instead of converging to the reverse-bias saturation current
Mott–Schottky ZnO dopant density	10¹⁴–10¹⁶ cm⁻³
Mott–Schottky built-in potential	0.6–0.9 eV
Bulk ZnO Fermi-level–conduction-band energy separation	Approximately 0.15 eV
Capacitance–voltage Schottky barrier	0.75–1.05 eV
Estimated zero-bias depletion-layer thickness	80–200 nm
Current–voltage and Mott–Schottky, ambient-pressure N2 or CO2 thermal cycling	The junction remained rectifying with increasing reverse-bias current at increasing temperature and no irreversible changes; the 0.42 eV Schottky barrier and approximately 4 × 10¹⁶ cm⁻³ dopant density persisted
Current–voltage, 20 % H2 in N2 or CO2 at 250 °C and cooling under the same atmosphere	The junction became ohmic and remained ohmic
Current–voltage, room-temperature N2 storage after 20 % H2 exposure	The junction remained ohmic
Current–voltage, room-temperature air exposure after 20 % H2 exposure	The junction returned to a rectifying Schottky junction on an approximately 24 h timescale
Current–voltage, heating under H2-free CO2 or N2 after 20 % H2 exposure	The junction returned to a rectifying Schottky junction
Current–voltage, 4 bar(a) H2 at 250 °C	The junction returned to a rectifying Schottky junction on a longer timescale
Current–voltage, 2.75 bar(a) H2 at 70 °C	The junction became ohmic within 1 h
Current–voltage, 0.5 bar(a) H2 at 70 °C	The junction remained a leaky Schottky junction
Current–voltage, H2 diluted in CO2 compared with H2 diluted in N2 at the same H2 partial pressure	The change in junction shunt resistance was slower with CO2
Current–voltage series resistance	0.1–1 Ω
Current–voltage and Mott–Schottky, octadecanethiol-treated junction after H2 exposure at 70 °C and 0.5 bar(a)	Schottky barrier height decreased and dopant density increased
Current–voltage, dichloromethane-treated junction after H2 exposure	Large losses to the apparent Schottky barrier height continued
Current–voltage and Mott–Schottky, 1:1 N2–H2 with 7.3 kPa water vapour at 70 °C	No significant changes in Schottky barrier height or dopant density; dopant density was unaltered or decreased