| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Wednesday Sessions |
| Session TF+EM+MI-WeM |
| Session: | Thin Film Processes for Electronics and Optics I |
| Presenter: | Firman Mangasa Simanjuntak, Tohoku University, Japan |
| Authors: | F.M. Simanjuntak, Tohoku University, Japan T. Ohno, Oita University, Japan S. Samukawa, Tohoku University, Japan |
| Correspondent: | Click to Email |
Transparent resistive random access memory (T-RRAM) devices have great potential as data storage for invisible electronics.1 ZnO material is one of the promising candidates for T-RRAM application due to its high transparency to the visible light.2 However, ZnO is an n-type semiconducting material which the intrinsic donor defects exist abundantly; consequently, the ZnO-based switching devices require high current compliance to operate as compared to another oxide system .1,3 The employment of the high current compliance is to facilitate the formation of conducting filament. Various efforts have been made to improve the ZnO-based switching memories, such as: by controlling the thickness, introducing a dopant(s), adjusting the gas ambient during deposition, stacking with various material(s) and structure(s).1 However, modulating the switching characteristics by controlling the sputtering power is still less overlooked. In this work, we investigated the influence of sputtering power in resistive switching characteristics of ZnO-based T-RRAM devices.
An approximately 50 nm thickness of ZnO films were deposited onto Indium Tin Oxide (ITO)-coated transparent substrates using conventional RF sputtering. Various sputtering power was used for the deposition while Ar/O2 ambient is maintained at 2/1 ratio. The deposition rate was measured using a surface profilometer. In order to fabricate sandwich device structure, circular gallium-doped ZnO (GZO) top electrodes were deposited onto the ZnO/ITO structure; patterned using a metal shadow mask with 150 µm in diameter. X-ray diffraction and X-ray photoelectron spectroscopy were used to investigate the crystal structure and the defect concentration of the ZnO films, respectively. A semiconductor device analyzer was used to measure the electrical characteristics of the devices.
XRD pattern indicated that all ZnO films show (002) oriented crystals. The devices made with higher sputtering power showed lower leakage current for OFF state and lowered current compliance to form the conducting filament (for ON state). We also found that the donor defects (oxygen vacancies and zinc interstitials) decrease as the sputtering power increases. These findings indicate that the sputtering power parameter cannot be simply overlooked in the T-RRAM fabrication.
References
1 F.M. Simanjuntak, D. Panda, K. Wei, and T. Tseng, Nanoscale Res. Lett. 11, 368 (2016).
2 F.M. Simanjuntak, O.K. Prasad, D. Panda, C.-A. Lin, T.-L. Tsai, K.-H. Wei, and T.-Y. Tseng, Appl. Phys. Lett. 108, 183506 (2016).
3 T. Ohno and S. Samukawa, Appl. Phys. Lett. 106, (2015).