A review of nucleation, growth and low temperature synthesis of diamond thin films

Abstract

Diamond thin films have outstanding optical, electrical, mechanical and thermal properties, which make these attractive for applications in a variety of current and future systems. In particular, the wide band gap, optical transparency and unusually high thermal conductivity of diamond thin films make them an ideal semiconductor for applications in current and future electronics. However, synthesis of diamond thin films with adequate quality remains a challenging task. Synthesis of diamond at low temperatures is even more challenging because of the difficulties in the nucleation and growth steps involved in diamond thin film deposition on a variety of substrates. Among the several deposition techniques for synthesising diamond films, plasma enhanced chemical vapour deposition is the most promising technique because of its potential for low temperature synthesis. Consequently, the first part of this paper reviews the current state of the nucleation and growth of diamond during chemical vapour deposition. A uniform and high nucleation density is a prerequisite for getting a good quality diamond film with significant growth rate. Also, since the process conditions for nucleation and growth steps are different, attempts are made in this review to identify the important parameters responsible for enhancing the nucleation and growth rates of diamond film. Describing the indispensable need for low temperature growth of diamond film, the second part of the paper reviews the research on the growth of diamond thin films at low temperatures. In spite of the slower kinetics at lower deposition temperatures, an attempt is made to identify the key processing conditions, which enhance the low temperature growth process. In addition, the mechanisms of diamond nucleation and growth are discussed based on the observations from in situ characterisation techniques such as Fourier transform infrared reflection absorption spectroscopy, real time spectroscopic ellipsometry and molecular beam mass spectroscopy.

Diamond Nucleation and Seeding Techniques: Two Complementary Strategies for the Growth of Ultra-thin Diamond Films

“…(iii) Finally, the production of non-volatile graphitic species was suggested, which could act as precursors for nucleation. 42 A surface study on scratched Si (100) by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and SEM well demonstrated the coexistence of two pathways: a seeding pathway occurring by direct growth from part of the Chapter 10 diamond seeds left by the mechanical pretreatment, and a nucleation pathway taking place through a stepwise process, including the formation of nucleation sites suitable for diamond nuclei. 79 These aspects will be further described in the section on seeding techniques (section 10.3).…”

“…4,42 In some studies heteroepitaxial growth was achieved. 43 This research field will be further discussed (section 10.2.4).…”

“…42 The diamond crystalline quality is strongly limited by the formation of a silicon carbide interlayer under CVD (section 10. …”

Microinjection Molding of Enhanced Thermoplastics

“…It detains an extreme mechanical hardness (ca. 90 GPa) and wear resistance, one of the highest bulk modulus (1.2 × 10 12 N.m −2 ), the lowest compressibility (8.3 × 10 −13 m 2 N −1 ), the highest room temperature thermal conductivity (2 × 10 3 W m −1 K −1 ), a very low thermal expansion coefficient at room temperature (1 × 10 −6 K) and is very resistant to chemical corrosion (Das & Singh, 2007;Grácio et al, 2010).…”

“…It possesses a high mechanical hardness and wear resistance, high thermal conductivity and is very resistant to chemical corrosion. Its properties and their optimization by means of the deposition process, in order to fulfill the application requisite have been investigated by several research teams (Ahmed et al, 2006;Das & Singh, 2007;Gracio et al, 2010). Some successful work has already been performed on the evaluation of diamond coating on molding tools in special for micro-featured tools (Neto, 2008b(Neto, , 2008c(Neto, , 2009).…”