Energy Quantization in Solution‐Processed Layers of Indium Oxide and Their Application in Resonant Tunneling Diodes. (2nd February 2016) - Labram, John G.
Abstract : The formation of quantized energy states in ultrathin layers of indium oxide (In2 O3 ) grown via spin coating and thermally annealed at 200 °C in air is studied. Optical absorption measurements reveal a characteristic widening of the optical band gap with reducing In2 O3 layer thickness from ≈43 to ≈3 nm in agreement with theoretical predictions for an infinite quantum well. Through sequential deposition of In2 O3 and gallium oxide (Ga2 O3 ) layers, superlattice‐like structures with controlled dimensionality and spatially varying conduction band characteristics are demonstrated. This simple method is then explored for the fabrication of functional double‐barrier resonant tunneling diodes. Nanoscale current mapping analysis using conductive atomic force microscopy reveals that resonant tunneling is not uniform but localized in specific regions of the apparent device area. The latter observation is attributed to variation in the layer(s) thickness of the In2 O3 quantum well and/or the Ga2 O3 barrier layers. Despite the nonidealities, the tremendous potential of solution‐processable oxide semiconductors for the development of quantum effect devices that have so far been demonstrated only via sophisticated growth techniques is demonstrated. Abstract : The existence of quantized energy states in ultrathin, solution‐processed layers of indium oxide is demonstrated. For layers below a critical thickness threshold a widening of the optical band gap is observed experimentally and in calculations. Sequential deposition of indium oxide and gallium oxide layers forms double‐barrier resonant tunneling diodes that exhibit negative differential conductance under reverse and forward biases.