Growth of diamond by rf plasma-assisted chemical vapor deposition
- PDF / 3,255,723 Bytes
- 7 Pages / 593.28 x 841.68 pts Page_size
- 14 Downloads / 242 Views
A. B. Swartzlanderand A. J. Nelson Solar Energy Research Institute, Golden, Colorado 80401 (Received 27 June 1988; accepted 11 August 1988) A system has been designed and constructed to produce diamond particles by inductively coupled radio-frequency, plasma-assisted chemical vapor deposition. This is a low-pressure, low-temperature process used in an attempt to deposit diamond on substrates of glass, quartz, silicon, nickel, and boron nitride. Several deposition parameters have been varied including substrate temperature, gas concentration, gas pressure, total gas flow rate, rf input power, and deposition time. Analytical methods employed to determine composition and structure of the deposits include scanning electron microscopy, absorption spectroscopy, scanning Auger microprobe spectroscopy, and Raman spectroscopy. Analysis indicates that particles having a thin graphite surface, as well as diamond particles with no surface coatings, have been deposited. Deposits on quartz have exhibited optical bandgaps as high as 4.5 eV. Scanning electron microscopy analysis shows that particles are deposited on a pedestal which Auger spectroscopy indicates to be graphite. This is a phenomenon that has not been previously reported in the literature.
I. INTRODUCTION The production of diamond from low-pressure, low-temperature processes has become an important technology generating an increasing interest in the scientific community, as evidenced by the rapidly growing number of papers being published on this subject. '"9 The material has a wide variety of possible applications arising from its properties of high thermal conductivity, high transparency, extreme hardness, and high-temperature electronic characteristics. Recently, the largest research effort has been in the area of microwave plasma- and filament-assisted CVD processes, and results are generally characterized by Raman spectroscopy.1"4 Previous reports of rf plasma processes have suggested the need for rf power greater than 500 W and substrate temperatures generally greater than 800 °C.5-6 In addition to these methods of deposition, electron-assisted CVD, thermal plasma-assisted CVD, and filament-assisted microwave plasma CVD are methods that have also been investigated.7"9 In this paper we report on the preparation of diamond from CH 4 /H 2 gas mixtures via plasma-assisted CVD, and the analysis of the resulting material by absorption spectroscopy, scanning electron microscopy, Auger microprobe spectroscopy, and Raman spectroscopy.
II. EXPERIMENTAL A schematic diagram of the apparatus is shown in Fig. 1. The rf generator could inductively supply up to 500 W at 13.56 MHz. The reaction tube was quartz with a diameter of 14 mm and a length of approximately 30 cm surrounded by a concentric cooling tube of quartz J. Mater, Res. 3 (6), Nov/Dec 1988
http://journals.cambridge.org
with a diameter of 25 mm and a length of 20 cm in a horizontal geometry. The cooling jacket was also used as a convenient way to center the reaction tube within the induction coil. The induction
Data Loading...
