MBE Growth and Characterization of Device-Quality Thick InN Epilayers;Comparison between N-polarity and In-polarity Growth Processes

摘要

Epitaxy of InN films with N-polarity and In-polarity was investigated by RF-MBE with several in-situ monitoring/controlling systems.It was found that the epitaxy temperature for N-polarity growth could be as high as 600 deg C and this was about 100 deg higher than that for In-polarity case.This temperature difference in two polarities drastically affected not only the growth behaviors but also the properties of InN epilayers,i.e.N-polarity growth was preferable in both view-points.The step-flow-like surface morphology was achieved for the InN films grown with N-polarity at 580 deg C.The FWHMs of X-ray rocking curves for InN (002) and (102) of 5-8 mum-thick InN films grown in N-polarity were about 200-350 and 650-950 arcsec,respectively.The highest Hall mobility was above 2000 cm~2/V centre dot s with a background carrier concentration of l-2x10~(18)cm~(-3) at room temperature.For both polarity films,N-rich condition was necessary for the stable InN growth to obtain 5-8 mum-thick InN films.