Publications by April S. Brown.

Papers Published

  1. Doolittle, W.A. and Kropewnicki, T. and Carter-Coman, C. and Stock, S. and Kohl, P. and Jokerst, N.M. and Metzger, R.A. and Kang, S. and Lee, K. and May, G. and Brown, A.S., Growth of GaN on lithium gallate substrates for development of a GaN thin compliant substrate, Materials Research Society Symposium - Proceedings, vol. 482 (1997), pp. 283 - 288 .
    (last updated on 2007/04/14)

    Abstract:
    The GaN on LGO system is the near perfect template (due to extremely high etch selectivity) for developing a viable thin film/compliant GaN substrate. Herein, we report on our efforts to grow GaN on LGO, including improvement of the microscopic surface morphology using pre-growth pretreatments. We also report on the first transferred thin film GaN substrate grown on LGO, transferred off of LOG, and mounted on GaAs. With this approach, (InAl)GaN alloys can be grown on thin GaN films, implementing a truly `compliant' substrate for the nitride alloy system. In addition, the flexibility of bonding to low cost Si, metal or standard ceramic IC packages is an attractive alternative to SiC and HVPE GaN substrates for optimizing cost verses thermal conductivity concerns. We have demonstrated high quality growth of GaN on LGO. X-Ray rocking curves of 145 arc-seconds are obtained with only a 0.28 µm thick film. We present data on the out of plane crystalline quality of GaN/LGO material. Likewise, we show 2 orders of magnitude improvement in residual doping concentration and factors of 4 improvement in electron mobility as compared to the only previously reported electrical data. We show substantial vendor to vendor and intra-vendor LGO material quality variations. We have also quantified the desorption of Ga and Li from the surface of LGO at typical growth temperatures using in situ desorption mass spectroscopy and XPS.

    Keywords:
    Semiconductor growth;Substrates;Thin films;Morphology;Semiconductor doping;Desorption;Mass spectrometry;X ray photoelectron spectroscopy;Semiconducting films;Nitrides;