Positive-bias enhanced growth of high quality diamond films by microwave plasma chemical vapor deposition

Enhancement was observed in the grain size, the growth rate and the (100) grain orientation of diamond films on Si (100) when a positive bias of 100–200 V was applied to the substrates during the microwave plasma chemical vapor deposition (MPCVD) of diamond films. The positive bias was found to be effective also for the growth of B-doped diamond films of good electrical properties. The hole Hall mobility of a diamond film grown with zero bias was around 100 cm2/V s while that of a sample with 200 V positive biasing reached 1000 cm2/V s. This mobility value belongs to the highest ever reported for diamond films on Si. The main effects of the positive bias during the MPCVD diamond growth were concluded to be a suppression of ion impinging into the substrate and an increased electron collision which would enhance the radical formation on the growing diamond films.