Effect of linear antenna chemical vapor deposition process parameters on the growth of nanocrystalline diamond-on-GaN films

Abstract

The present work will systematically study the effect of different linear antenna microwave plasma enhanced chemical vapor deposition (LACVD) processing parameters on the optimal deposition of the diamond films. The low pressure and low temperatures of LACVD growth conditions is expected to deposit diamond films on otherwise reactive gallium nitride (GaN) surfaces, without any intermediate nitride buffer layer. First, the distances between the quartz tube and the samples put on the stage are varied (3-15 cm), which has a direct impact on the substrate temperature (415 degrees-300 degrees - 300 degrees C). Thereafter, the microwave input power was also altered (1.5-2.8 kW) to attain low substrate temperatures. It was found that 300 degrees C is the temperature limit, which can be attained by heating only with microwave plasma when the substrates are kept farthest (15 cm) away from the liner antenna quartz tube. An additional heater was used under the stage for rapidly achieving such minimum substrate temperatu