Expansion Growth of <110>-Oriented Single Crystal Diamond

Abstract

The (110) single crystal diamond has certain advantages over the mainstream (100) diamond in the application of electronic devices, but there was rare research on its epitaxy. The growth condition of (110) diamond was optimized, resulting in CH4/H2=4%&O2/H2=0.5%. Growth of 5 hours revealed the dominance of (100) and (111) facet growth in <110> epitaxy on top surface with a growth rate of 16.6 μm/h. Meanwhile, at (110) and (100) substrate sides, the corresponding epi-crystal sides were grown to (100) and (111) surfaces, resulting in a shrinkage of (110) top surface. However, a 100 hours growth on a 5 mm × 5 mm substrate led to a crystal with top surface first expanding to 7.03 mm × 8.12 mm and then shrinking, finished with maximum thickness of 3.1 mm and crater-like top surface covered by large ridges with height of ~1 mm along <100> direction and polycrystals. A 1-mm-thick (110) diamond plate was cut from the largest expansion part, and showed the width of the X-ray rocking curve much reduced than that of substrate at different planes. This first report of expansion growth of the (110) diamond could provide new insight and way of fabrication of diamond semiconductor materials and devices.

Keywords: (110) diamond, single crystal growth, expansion, MPCVD