Author/Authors :
Lin، نويسنده , , J.C. and Su، نويسنده , , Y.K. and Lan، نويسنده , , W.H. and Kuan، نويسنده , , T.M. and Chen، نويسنده , , W.R. and Cheng، نويسنده , , Y.C. and LIN، نويسنده , , W.J. and Tzeng، نويسنده , , Y.C. and Shin، نويسنده , , H.Y.، نويسنده ,
Abstract :
The effects of the GaN epilayers and LED structures grown by metalorganic chemical vapor deposition on 1° off c-plane sapphire substrate were studied. Although the 1° off-axis GaN sample has slightly rough surface morphology, it has narrower full-width at half-maximum (FWHM) of X-ray asymmetrical reflection (10–12), higher mobility, lower compensating acceptor concentration and lower etching pits densities (EPD) than the on-axis GaN sample. And it also has lower etching pits densities (EPD). To reduce the threading dislocations in GaN films grown on vicinal substrates is attributed. A very weak yellow luminescence is observed in photoluminescence (PL) spectra of 1° off-axis GaN sample. Finally, comparing to LED structures grown on on-axis c-plane sapphire substrates, the LED structures grown on 1° off substrate show a blue shift of PL wavelength and 2.6 times stronger in PL intensity. The electroluminescence (EL) intensity of 1° LED sample rises faster in small amount of driving current region.
