Bandgap Engineering of Ga2O3 by MOCVD Through Alloying with Indium

TL;DR

This paper explores how adding indium to gallium oxide changes its electronic properties, enabling bandgap engineering for better semiconductor performance.

Contribution

The study demonstrates bandgap tuning in IGO alloys via MOCVD and reveals the impact of In on electronic transport properties.

Findings

Adding In reduces the optical band gap of IGO, confirmed by DFT calculations.

H2 annealing induces n-type conductivity in IGO films across all In percentages.

Higher In content increases electron mobility due to reduced effective mass.

Abstract

Ga2O3 and In2O3 are vital semiconductors with current and future electronic device applications. Here, we study the alloying of In2O3 and Ga2O3 (IGO) and the associated changes in structure, morphology, band gap, and electrical transport properties. Undoped films of IGO were deposited on sapphire substrates with varying indium (In) percentage from zero to 100% by metal-organic chemical vapor deposition (MOCVD). Some films were annealed in H2 to induce electrical conductivity. The measurements showed the optical band gap decreased by adding In; this was confirmed by density functional (DFT) calculations, which revealed that the nature of the valence band maximum and conduction band minimum strongly relate to the chemistry and that the band gap drops by adding In. The as-grown films were highly resistive except for pure In2O3, which possesses p-type conductivity, likely arising from In vacancy-related acceptor states. N-type conductivity was induced in all films after H-anneal. DFT calculations revealed that the presence of In decreases the electron effective mass, which is consistent with the electrical transport measurements that showed higher electron mobility for higher In percentage. The work revealed the successful band gap engineering of IGO and the modification of its band structure while maintaining high-quality films by MOCVD.

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