| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Tuesday Sessions |
| Session TF+AS-TuM |
| Session: | Special Session in Honor of Paul Holloway: Luminescent Materials Growth, Synthesis and Characterization |
| Presenter: | Markku Leskela, University of Helsinki, Finland |
| Authors: | M.A. Leskela, University of Helsinki, Finland M.K. Ritala, University of Helsinki, Finland |
| Correspondent: | Click to Email |
In optoelectronics, i.e. in electronic devices and systems that emit, detect and control light, the active materials are usually II-VI or III-V semiconductors. Historically in Atomic Layer Deposition (ALD) or Atomic Layer Epitaxy (ALE) as it was called in 70s and 80s, zinc sulfide has been very important material. The ALE technology was developed for manufacturing AC driven thin film electroluminescent displays [1]. Monochromic yellow-black displays based on ZnS:Mn luminescent layer sandwiched between dielectrics and electrodes has been manufactured industrially by ALD continuously since 1984. Besides the luminescent layer, the high-quality oxide layers made by ALE have had an important role as dielectrics and passivation layers in the success of the ACTFEL displays. Multicolor displays can be realized by filtering the broad emission band of ZnS:Mn or using other luminescent material, e.g. green-emitting ZnS:Tb. Despite of intense studies in 1980s and 1990s full-color ACTFEL devices could not been developed to the mass production level because of the missing efficient deep blue-emitting phosphor. Today the strongest developing application area in thin film EL displays is transparent displays used widely in different vehicles [2]. This motivates to re-examine the color displays.
Deposition of epitaxial films of III-V materials is possible with ALD as demonstrated already in 1985 [3]. Processes have been developed for all III-V materials using alkyl compounds for group III metals and hydrides for group V elements as precursors. The advantages of ALD processing compared to MOCVD or MBE have remained, however, modest because of the carbon contamination.
Transition metal dichalcogenides are emerging 2D materials that are potential channel materials in field-effect transistors as well as phototransistors and other optoelectronic devices. The bottle-neck in the large use of these two-dimensional materials is the lack of scalable, low-temperature process for high-quality, large-area films. ALD has been studied as a solution for these problems [4].
In other optoelectronic devices the ALD films find most often use in passivation and encapsulation. Silicon based solar cells is a good example of the former [5] and OLED displays from the latter application area [6].
References
1. T. Suntola, J. Anson, US Patent 4,058,430 (1977).
2. S. Bush, Electronics Weekly. Com, Jan 20, 2017.
3. J.-I. Nishizawa, H. Abe, T. Kurabayashi, J. Electrochem. Soc. 132, 1197 (1985).
4. Y. Kim et al. Sci. Reports 6, 18754 (2016).
5. G. Dingemans, W.M.M. Kessels, J. Vac. Sci Technol. 30, 040802, (2012).
6. J. Meier et al. Appl. Phys. Lett. 94, 233305 (2009).