Growth of adherent diamond films on optically transparent sapphire substrates

Abstract

The growth of continuous adherent diamond thin films on optically transparent substrates is important for the development of corrosion and erosion resistant infrared windows for many applications. Until now, the growth of adherent diamond films on optically transparent substrates like sapphire has been unsuccessful due to the large thermal mismatch between the film and the substrate and the absence of an interfacial carbide ‘‘glue’’ layer. By employing a low temperature (500–550 °C), low pressure (∼1 Torr) electron–cyclotron–resonance chemical-vapor-deposition process, and utilizing a dispersed–particulate diamond suspension for nucleation, adherent diamond thin films have been fabricated on sapphire substrates. Raman spectroscopy showed that the diamond peak was shifted approximately 6 cm−1 above its equilibrium position, suggesting the presence of very large compressive stresses (∼3.2 GPa) in the film.

Chemical vapor deposition of diamond on an adamantane-coated sapphire substrate

“…Nevertheless, Singh et al showed that low temperature growth can obtain adherent diamond lms on optically transparent sapphire. 23 Several approaches, such as utilizing in situ two-step hot lament chemical vapor deposition or polishing the substrate surface carefully and by in situ pre-deposition of a carbon layer on the alumina substrate surface, or using the activated species transport (AST) method which supplies activated diamond species to the substrate in a plasma ame, were proposed to overcome the problem, but they still resulted in a relatively low nucleation density ($10 6 -10 7 particles per cm 2 ). [16][17][18][19][20] We have previously shown enhanced nucleation of diamond on adamantane-coated Si at relatively low temperatures 21,22 which may mitigate the thermal stress.…”

Characteristics of Diamond Deposition on Al2O3, Diamond-like Carbon, and Q-Carbon

“…Singh et al developed a low-temperature (500−550 °C) electron−cyclotron−resonance CVD process to grow diamond films on c-Al 2 O 3 to overcome the stress-related problems. 30 Even this low deposition temperature generates 3.5 GPa stress, which is enough to cause delamination in the weakly bonded diamond film on noncarbide-forming Al 2 O 3 . The thermal misfit strain is negative in the diamond−Al 2 O 3 system, referring to the compressive strain.…”

An Insight into Grain Refinement Mechanism of Ultrananocrystalline Diamond Films Obtained by Direct Current Plasma-Assisted Chemical Vapor Deposition

“…The nanocrystalline diamond (NCD) films are synergistic combinations of diamond and nanocrystalline thin film microstructures, which have given many innovative applications . An innovative process using unique Ar‐rich gas chemistry via microwave plasma chemical vapor deposition (MPCVD) promoted the synthesis of NCD with grain size as small as few nano‐meters, named ultrananocrystalline diamond (UNCD) film .…”