Influence of initial growth stages on AlN epilayers grown by metal organic chemical vapor deposition

• AIN layers of thickness of about 2 mu m have been grown with AIN nucleation layers (NLs) on (001) sapphire substrates using metal organic chemical vapor deposition. Increasing the AlN-NL deposition temperature from 850 to 1250 degrees C has been found to have significant effect on the surface morphology and the structural quality of the AIN layers. The surface morphology of the AlN-NLs and the AIN layers has been assessed using atomic force microscopy (AFM). The AM images of the AlN-NLs reveal the coalescence pattern of NLs. AM images of the AlN layers and the in-situ reflectance measurement disclose the surface morphology and the growth pattern of the AIN layers, respectively. Smooth surface with macro-steps and terrace features has been achieved for the AIN layer grown on the NL deposited at 950 degrees C. The structural quality of AIN layers has been studied by high resolution X-ray diffraction and Raman spectroscopy. The screw dislocation density from (002) reflection and the average edge dislocation density from (102), (302) and (100) reflections of the AIN layer on NL deposited at 950 degrees C are estimated to be 9 x 10(7) cm(-2) and 4.4 x 10(9) cm(-2), respectively. Lateral correlation length (L) is calculated from the (114) reciprocal space mapping of the AIN layers and correlated with the edge dislocation density of the AIN layers. Raman E-2 (high) phonon mode indicates compressive strain in the AIN layers grown on the NLs deposited at various temperatures. From this work, it has been inferred that the uniform coalescence of the nucleation islands and the complete coverage of AlN-NL determine the surface morphology and the structural quality of the subsequently grown AIN layers.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering (hsv//eng)

Nyckelord

A1. Atomic force microscopy

A1. Nucleation islands

A1. Surface structure

A3. Metalorganic chemical vapor deposition

B2. Semiconducting aluminum compounds

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)