| AVS 58th Annual International Symposium and Exhibition | |
| Electronic Materials and Processing Division | Friday Sessions |
| Session EM+SS-FrM |
| Session: | Surfaces and Materials for Next Generation Electronics |
| Presenter: | Rachael Myers-Ward, Naval Research Laboratory (NRL) |
| Authors: | R.L. Myers-Ward, Naval Research Laboratory (NRL) E.A. Imhoff, Naval Research Laboratory (NRL) J.D. Caldwell, Naval Research Laboratory (NRL) L.O. Nyakiti, Naval Research Laboratory (NRL) V.D. Wheeler, Naval Research Laboratory (NRL) K.D. Hobart, Naval Research Laboratory (NRL) C.R. Eddy, Jr., Naval Research Laboratory (NRL) D.K. Gaskill, Naval Research Laboratory (NRL) |
| Correspondent: | Click to Email |
To avoid defects such as polytype inclusions or dislocations, the epitaxial growth of 3C-SiC requires a lattice-matched, perfect substrate. One solution to this problem is to use step-free mesas of 4H-SiC as 3C-SiC lattice templates [1]. In this work, we describe the formation of large area step-free mesas and the subsequent nucleation and growth of 3C-SiC layers. A powerful array of tools were utilized to characterize the properties of these layers including Nomarski microscopy, secondary electron microscopy (SEM), atomic force microscopy and X-Ray diffractometry. Micro-photoluminescence (µ-PL) was employed to investigate the presence of electronic defects and identification of polytype, enabling us to obtain information about the structural and electronic properties on a micron-sized length scale.
On-axis 4H-SiC substrates were initially patterned and reactive ion etched to produce hexagonal and square shaped mesas with varying widths ranging from 40 to 400 µm (400% greater area than previous reports), and heights from 2 to 5 µm. Homoepitaxial layers were grown on the mesas in an Aixtron VP508 horizontal hot-wall chemical vapor deposition reactor using the standard chemistry of silane and propane in order to grow out the steps on the mesas. The homoepitaxial layers were terminated at the mesa step edge and further growth is prohibited. The films were grown at 2µm/hr and the pressure and temperature were 100 mbar and 1580°C, respectively. The yields of 200 µm width 4H-SiC step-free mesas was ~95%. Heteroepitaxial 3C-SiC was grown 2 µm thick on the homoepitaxy (4H-SiC) by means of reducing the growth temperature to 1450°C, while maintaining 100mbar.
Under Nomarski evaluation, ~ 18% of the 200 µm wide 3C-SiC mesas appeared to be step-free. Micro-PL maps were used to confirm the presence of 3C-SiC, where uniform 3C-SiC was detected across the entire mesas. X-ray rocking curves also indicated 3C-SiC, with the FWHM of the SiC (111) being ~21", indicating good quality material.
Yield maps for the 200 and 400 µm mesas will be presented. In addition, real color PL imaging will be used to determine the types of defects within the mesas which displayed lower PL intensity regions of 3C-SiC. Lastly, initial results of Schottky rectifiers performance made on the layers will given.
References
[1] J. A. Powell, et al., Appl. Phys. Lett. 77, 1449 (2009).