| AVS 66th International Symposium & Exhibition | |
| Thin Films Division | Tuesday Sessions |
| Session TF+AP-TuM |
| Session: | ALD and CVD: Precursors and Process Development |
| Presenter: | Samantha G. Rosenberg, American Society for Engineering Education (residing at U.S. Naval Research Laboratory) |
| Authors: | S.G. Rosenberg, American Society for Engineering Education (residing at U.S. Naval Research Laboratory) D.J. Pennachio, University of California at Santa Barbara E.C. Young, University of California at Santa Barbara Y.H. Chang, University of California at Santa Barbara H.S. Inbar, University of California at Santa Barbara J.M. Woodward, U.S. Naval Research Laboratory Z.R. Robinson, SUNY Brockport J. Grzeskowiak, University at Albany - SUNY C.A. Ventrice, Jr., SUNY Polytechnic Institute C.J. Palmstrøm, University of California at Santa Barbara C.R. Eddy, Jr., U.S. Naval Research Laboratory |
| Correspondent: | Click to Email |
III-N semiconductors are well suited for applications in several important technological areas, including high current, normally-off power switches.1,2 Such devices require heterostructures not readily achievable by conventional growth methods. Therefore, we have developed a technique adapted from atomic layer deposition (ALD), called plasma-assisted atomic layer epitaxy (ALEp).2 Using surface science techniques, we strive to develop not only a fundamental understanding of the ALEp growth process but also complimentary atomic level processes (ALPs) that will result in the best preparation method for a pristine GaN starting surface for ALEp.
Here we employ in-situ and in-vacuo surface science studies of GaN substrate preparation to advance fundamental understanding of the ALEp process. Having optimized our GaN surface preparation (gallium flash off ALP),3 we conduct in-vacuo X-ray photoelectron spectroscopy (XPS), reflection high-energy electron diffraction (RHEED), and scanning tunneling microscopy (STM) studies in the Palmstrøm Lab at UCSB to further refine both our process and our understanding. Preliminary XPS results show that a GFO ALP conducted at 250°C for 12 cycles reduces the oxygen content by 5% but shows no reduction in the carbon content, while a GFO ALP conducted at 400°C for 30 cycles reduces the carbon content by 60% but shows no reduction in the oxygen content. Other XPS results show that our previously reported optimal GFO ALP results in a ~25% reduction of carbon, while a similar 25% reduction of oxygen was achieved using a GFO ALP with or without TMG. We have also conducted comparable temperature program desorption (TPD) and low energy electron diffraction (LEED) experiments at SUNY Polytechnic Institute to correlate structural and chemical changes that occur on GaN surfaces treated with our GFO ALP. TPD shows that NH3 is released from GaN surfaces not subjected to GFO ALP as it is heated past 150°C, while GFO ALP GaN surfaces show no NH3 release upon subsequent TPD experiments. Both GaN surfaces, before and after TPD, show an unreconstructed 1x1 diffraction pattern in LEED.
1. N. Nepal, et al., Appl. Phys. Lett. 103, 082110 (2013)
2. C. R. Eddy, Jr, et al., J. Vac. Sci. Technol. A 31(5), 058501 (2013)
3. S. Rosenberg, et. al., J. Vac. Sci. Technol. A 37, 020908 (2019)