Invited Paper VT-TuA11
Defect Manipulation to Control Energy Processes in Electronic Materials

Tuesday, October 22, 2019, 5:40 pm, Room A213

The control of native point defects in advanced electronic materials and device architectures is critical to a wide array of energy intensive processes including generation, transport, storage, switching, and display. AVS research in electronic materials surfaces and interfaces at the nanoscale has played an important role in this arena. Defect control of transparent conducting oxides such as ZnO for smart windows and heads-up displays have revealed how to create homojunctions with high electron mobility 2-dimensional interfaces.¹ Surface/interface techniques enable identification and control of native defects in Ga₂O₃,² outlooked for RF power amplification and power switching. Defect control has enabled creation of 2-dimensional hole gases at LaAlO₃/SrTiO₃ interfaces, opening an avenue to new architectures for complex oxide electronics. Depth-resolved defect measurements in V₂O₅ battery electrode films reveal how lithiation introduces degenerate doping and secondary phase formation, integral to ion and charge transport inside next-generation nanoscale battery architectures.³ Direct, localized optical, and electrical measurements of ZnO nanowires – envisioned for wearable electronics and displays - show that native point defects inside the nanowire bulk and created at metal-semiconductor interfaces are electrically active^4,5 and play a dominant role electronically, altering the doping, carrier density along the wire length, and the injection of charge into the wire.⁶ Defects in all these materials can now be manipulated by ion beams, electric fields, remote oxygen plasmas, and nanoscale design, opening new avenues to control charge injection, transport, and storage.

1. G. M. Foster et al., “Direct Measurement of Defect and Dopant Abruptness at High Electron Mobility ZnO Homojunctions,” Appl. Phys. Lett. 109, 143506 (2016).

2. H. Gao et al., “ Optical Signatures of Deep Level Defects in Ga₂O₃,” Appl. Phys. Lett. 112, 242102 (2018).

3. H. Lee et al., “Direct observation of a two-dimensional hole gas at oxide interfaces,” Nature Materials 17, 231-236 (2018).

4. W.T. Ruane et al., “Defect Segregation and Optical Emission In ZnO Nanowiresand Microwires,” Nanoscale 8, 7631-7637 (2016).

5. A. Jarjour et al., Single Metal Ohmic and Rectifying Contacts to ZnO Nanowires: A Defect Based Approach,” Ann. Phys. (Berlin), 530, 1700335 (2018).

6. J.W. Cox et al., “Defect Manipulation to Control ZnO Micro-/Nanowire-Metal Contacts,” Nano Letters 18, 6974 (2018). DOI: 10.1021/acs.nanolett.8b02892