Laser-assisted recrystallization to improve the surface morphology of CdTe epitaxial layers
Laser-assisted recrystallization has been studied in order to improve the surface morphology of CdTe layers grown on sapphire substrates by metalorganic vapour phase epitaxy (MOVPE). The recrystallization was carried out by scanning the surface of as-grown CdTe MOVPE layers with an Ar ion laser beam ( = 514.5 nm) as the laser power varied in the 140 - 600 mW range. The irradiation time was in the range from 10 s to 5 min. The effect of the recrystallization layers' surface procedure on the structure has been investigated by scanning electron microscopy, Rutherford backscattering spectrometry and spectroscopic ellipsometry. Depending on the laser power and irradiation time, the recrystallization was shown to occur either within the entire layer thickness or on the layer surface. Due to recrystallization, the surface microrelief of the layers has been improved all over the recrystallized area and the surface roughness has been uniformly decreased from 1.5 m to 0.2 m. The data obtained show that it might be possible to engineer CdTe MOVPE layers using post-growth laser-assisted recrystallization, making them more suitable for infrared applications.