Growth of 2 um Crack-Free GaN on Si(111)Substrates by Metal Organic Chemical Vapor Deposition

A 2μm high quality crack-free GaN film was successfully grown on 2-inch Si(111)substrates by metal organic chemical vapor deposition with a high temperature AIN/graded-AlGaN multibuffer and an AIN/GaN superlattice interlayer.It is found that the structures,as well as the thicknesses of the multibuffer and interlayer,are crucial for the growth of a crack-free GaN epilayer.The GaN(0002)XRD FWHM of the crack-free sample is 479.8arcsec,indicating good crystal quality.An AlGaN/GaN heterostructure was grown and tested by Van der Pauw Hall measurement.The electron mobility of two-dimensional electron gas increases from 1928 cm^(2)/V.S to 12277cm^(2)/V s when the test-temperature decreases from room temperature to liquid nitrogen temperature.The electron mobility is comparable to that of AlGaN/GaN heterostructures grown on sapphire,and the largest value is obtained for an AlGaN/GaN/Si(111)heterostructure grown by metal organic chemical vapor deposition.