Evaluation of LEC and VGF-InAs substrates through surface defect characterization and epitaxy growth

Undoped InAs (100) substrate wafers prepared by liquid encapsulated Czochralski (LEC) and vertical temperature gradient freezing (VGF) methods have been studied and compared in their epi-ready state. The substrate surface defects have been analyzed by surface scanner KLA candela, Energy Dispersive X-Ray Spectroscopy (EDAX), Total-reflection X-ray fluorescence spectroscopy (TXRF), with an aim to find the contrast between LEC-InAs and VGF-InAs substrates. It is found that the VGF wafers have lower surface point defects and good stoichiometry compared with the LEC-wafer. VGF-InAs is more favorable to LEC-InAs for oxide thermal desorption and midwavelength infrared（MWIR）epitaxial layer growth with low defect density.