Multivariable study on homoepitaxial diamond growth using isotopically enriched carbon-13 gas mixtures
- PDF / 769,144 Bytes
- 6 Pages / 584.957 x 782.986 pts Page_size
- 31 Downloads / 188 Views
We report our observations on the homoepitaxial diamond growth by microwave plasma chemical vapor deposition (MPCVD) experiments on Type Ib diamond substrates conducted by varying three independent variables. In a feed gas mixture of H2, N2, O2, and 13CH4, the amount of nitrogen was varied in the range of 0 to 4000 ppm, the amount of methane was varied from 2% CH4/H2 to 6% CH4/H2, and the substrate temperature was varied in the range of 850 to 1200 C. We used isotopically enriched carbon-13 methane gas as the source of carbon in the plasma to clearly distinguish the grown diamond layer from the underlying substrate using Raman spectroscopy. The x-ray rocking curve measurements confirmed the homoepitaxial nature of the deposited layers with a slight increase in the full width at half-maximum for sample grown with the highest nitrogen content in the plasma. Optical and atomic force microscopy revealed dramatic changes in surface morphology with variation in each parameter. The nitrogen incorporation in carbon-13 diamond layers was monitored through photoluminescence spectroscopy of nitrogen–vacancy complexes. A twentyfold increase in diamond growth rate was clearly achieved in this multivariable study. I. INTRODUCTION
Homoepitaxial diamond growth continues to be a subject of intense research because of its wide range of potential applications in high-power electronic devices and solid-state electronics.1 The present study is motivated by finding optimal growth conditions needed for homoepitaxial diamond deposition for encapsulation of electrical microprobes on single-crystal diamond anvils. The high homoepitaxial diamond growth rates are needed to quickly encapsulate the electrical microprobes without any significant polycrystalline nucleation on the metallic surfaces. The goal behind such research has been to produce high-quality single-crystal diamonds with an emphasis on low deposition time, which translates into high growth rates. The recent advances in the microwave plasma chemical vapor deposition (MPCVD) of single-crystal diamond have enabled such possibilities. The introduction of nitrogen in the MPCVD plasmas has been extensively studied with enhancement in diamond growth rates.2–5 While the catalytic effect of nitrogen has been reported by various authors,5–8 it is to be noted that earlier investigations have used only up to few hundred parts per million (ppm) of nitrogen. Our study extends this observation further by adding up to 4000 ppm nitrogen in the feed gas mixture. Some groups
II. EXPERIMENTAL DETAILS
Commercially available synthetic high-pressure hightemperature synthesized type Ib diamond plates were used as substrates for homoepitaxial diamond growth
a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2009.0052 J. Mater. Res., Vol. 24, No. 2, Feb 2009
http://journals.cambridge.org
have reported growth rates ranging up to 50–100 mm/ hour.2,3,9 However, the previous research by these authors used higher microwave powers and relatively higher pressures dur
Data Loading...
