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Keywords:

  • InN films;
  • MOCVD;
  • growth conditions

Abstract

In order to optimize the growth conditions, the effect of the most important growth parameters such as growth temperature, pressure and V/III ratio on MOCVD-grown InN was investigated. A series of samples were grown by changing the growth temperature from 500 °C to 550 °C at fixed growth pressure of 800 mbar and V/III ratio of 145000. An improvement of electrical properties with temperature increment was noted. The highest mobility of 1200 cm2/Vs was achieved at 550 °C with a bulk carrier concentration of 4.32 x 1018 cm-3. The effect of V/III ratio on In droplet formation and on carrier concentration was also studied. At fixed temperature of 520 °C, reactor pressure of 200 mbar and at fixed NH3 flow of 3 slm, a rising TMIn flow from 1.2 µmol/min to 2.0 µmol/min results in a carrier concentration increment from 6.06 x 1018 cm-3 to 1.33 x 1019 cm-3and a decrement of the mobility from 430 cm2/Vs to 348 cm2/Vs. X-ray diffraction measurements show that the intensity associated with In droplets on the surface is rising with increasing TMIn flow. The effect of reactor pressure on InN growth was also examined. A high sensitivity to growth pressure for crystalline quality of InN was observed. The full width at half maximum (FWHM) values of InN (0002) reflexes decreased with increasing reactor pressure. With increasing growth pressure above 200 mbar, FWHM of around 275 arcsec of InN (0002) was achieved. This FWHM value is the lowest reported in literature for MOCVD-grown InN so far. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)