Strong Confined Optical Emission and Enhanced Thermoelectric Power Factor by Coupling Homologous In2O3(ZnO)m with In-Doped ZnO Channels into Heterojunction Belts

Abstract

Multifunctional nanodevices integrated with excellent optoelectric and thermoelectric properties are highly demanded for developing next generation self-powered optoelectronics. In the work, we demonstrate the viability of a coupled structure of homologous In2O3(ZnO)m with In-doped ZnO into heterojunction belts synthesized by alloy-evaporation deposition, offering multiple functions with strong confined optical emissions and high power factors. Energy-filter secondary electron images reveal a five-layer contrast in the width direction of the belts due to different ionization energies corresponding to In2O3(ZnO)m/In:ZnO/ZnO/In:ZnO/In2O3(ZnO)m, as confirmed by transmission electron microscopy analysis. The indium-doped ZnO channels confined in two sides behave like quantum wells through band alignment, and become predominant in the main UV emission at 385 nm, as revealed by cathodoluminescence spectroscopic imaging. More intriguingly, this novel heterostructure provides an ideal pathway to enhance electron conduction through the indium doped ZnO layer, and the homologous In2O3(ZnO)m layer contains numerous interfaces to impede phonon transportation. In this way, the power factor of the heterostructure is greatly enhanced to be 2.07 × 10–4 W m–1 K–2 at room temperature, as compared to about 1.03 × 10–5 W m–1 K–2 for the undoped ZnO nanowires. This unique heterostructure achieved by a facile one-step growth process offers a new concept for designing devices by manipulating photons via coupling with electrons and phonons.