Thickness dependent dislocation, electrical and optical properties in InN films grown by MOCVD

InN thin films with different thicknesses are grown by metal organic chemical vapor deposition, and the dislocations, electrical and optical properties are investigated. Based on the model of mosaic crystal, by means of X-ray diffraction skew geometry scan, the edge dislocation densities of 4.2 x 10(10) cm(-2) and 6.3 x 10(10) cm(-2) are fitted, and the decrease of twist angle and dislocation density in thicker films are observed. The carrier concentrations of 9 x 10(18) cm(-3) and 1.2 x 10(18) cm(-3) are obtained by room temperature Hall effect measurement. V-N is shown to be the origin of background carriers, and the dependence of concentration and mobility on film thickness is explained. By the analysis of S-shape temperature dependence of photoluminescence peak, the defects induced carrier localization is suggested be involved in the photoluminescence. Taking both the localization and energy band shrinkage effect into account, the localization energies of 5.05 meV and 5.58 meV for samples of different thicknesses are calculated, and the decrease of the carrier localization effect in the thicker sample can be attributed to the reduction of defects.

National Basic Research Program of China 2006CB6049 National High Technaology Research and Development Program of China 2006AA03AI03 2006AA03AI 18 National Nature Science Foundation of China 60721063 60731160628Research Funds from NJU-Yangzhou Institute of Opto-electronics 2008003 20080072008008Project supported by the National Basic Research Program of China (Grant No. 2006CB6049), National High Technaology Research and Development Program of China ( Grant Nos. 2006AA03AI03, 2006AA03AI 18), the National Nature Science Foundation of China Grant Nos. 60721063, 60731160628), the Research Funds from NJU-Yangzhou Institute of Opto-electronics ( Grant Nos. 2008003,2008007,2008008)