Systematic Oxidation of Bi₂O₂Se Semiconductors with Metal Oxide Layers

Bismuth oxyselenide (Bi₂O₂Se) has emerged as a promising layered semiconductor due to the high carrier mobility, stability, and potential for its integration into next generation electronic devices. However, the manufacturing processing for this material remains incomplete. Particularly, the forces governing oxidating and phase transformation. Understanding these mechanisms is essential for developing reliable synthesis strategies. In this work, the systematic oxidation of bismuth selenium and bismuth oxy-selenide thin films were studied with controlled oxygen reservoir and oxygen scavengers. The oxygen reservoir material was hafnium oxide (HfO₂), which was placed on bismuth selenide (Bi₂Se₃) to oxidize into Bi₂O₂Se. The oxygen receiver was a titanium (Ti) capping layer on Bi₂O₂Se to allow phase transformation into Bi₂Se₃. These materials were annealed at various temperatures in a controlled environment to study the oxidation reaction and the driving forces behind them.
Thin films of Bi₂Se₃ and Bi₂O₂Se were synthesized by chemical vapor deposition (CVD) and pulsed laser deposition (PLD). The capping layers were deposited with atomic layer deposition (ALD) and sputtering.
Results show successful oxidation and scavenging with the metal oxide layers as nickel oxide (NiO), Titanium (Ti) and hafnium oxide was utilized (HfO₂)