| AVS 66th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Tuesday Sessions |
| Session EM+OX+TF-TuA |
| Session: | Nikolaus Dietz Memorial Session: Wide and Ultra-wide Band Gap Materials and Devices |
| Presenter: | Charles R. Eddy, Jr., U.S. Naval Research Laboratory |
| Authors: | C.R. Eddy, Jr., U.S. Naval Research Laboratory S.G. Rosenberg, American Society for Engineering Education (residing at U.S. Naval Research Laboratory) J.M. Woodward, American Society for Engineering Education (residing at U.S. Naval Research Laboratory) K.F. Ludwig, Boston University N. Nepal, U.S. Naval Research Laboratory |
| Correspondent: | Click to Email |
Wurtzite indium nitride (InN) has direct bandgap of about 0.7 eV with large phonon gap and is an attractive semiconductor material for application in various areas, e.g. optical, electrical, optoelectronic, and spintronic device technologies [1]. InN and its alloys with GaN and AlN (III-N) have therefore found application in a variety of technologies such as high power transistors, emitters, detectors, and solar-cells. The relatively high growth temperature of common III-N synthesis techniques has impeded further development and application of the materials due to challenges with miscibility gaps and strain related to thermal expansion mismatch with non-native substrates. To address these challenges, plasma assisted atomic layer epitaxy (PA-ALEp) offers a new approach to low temperature III-N growth and can be used to epitaxially grow InN by using alternative pulses of trimethylindium and nitrogen plasma [2]. We report on development of the PA-ALEp process for InN growth on sapphire and gallium nitride substrates demonstrating the self-limited growth windows as a function of temperature and pulse durations in the process. We benchmark the quality of our films compare to those grown by Dietz et al. by high pressure CVD [3]. The process produces quality, crystalline semiconductor films with properties comparable to those grown by conventional methods at temperatures roughly 2X higher. Beyond that, the PA-ALEp process affords realization of InN containing ternary nitrides with aluminum and gallium that are not possible with conventional growth methods. Further, the unique, non-thermal equilibrium process enables realization of cubic (rock salt) phases on InN. In order to better understand nucleation and growth mechanisms involved in the PA-ALEp process, we employ in situ X-ray scattering methods using synchrotron radiation. We have determined that the growth proceeds largely by a Stranski-Krastinov process on either sapphire or gallium nitride. Further, we have investigated the impact of components of the PA-ALEp cycle on the growth process [4], in particular the plasma pulse time. Here we see that pulse time can affect the nature of nucleation from bimodal nucleation to single mode nucleation to degraded growth as pulse time increases from 15 seconds to 30 seconds. These and other nucleation and growth behaviors will be highlighted.
[1] O. Ambacher, J. Phys. D: Appl. Phys. 31, 2653 (1998).
[2] N. Nepal, et al., Cryst. Growth Design 13, 1485 (2013).
[3] N. Dietz, et al., Phys. Status Solidi B 242, 2985 (2005).
[4] N. Nepal, et al., J. Vac. Sci. Technol. A 37, 020910 (2019).