Measurement of stresses and critical thickness of MBE-grown (013)HgTe layer by nonlinear diagnostic methods

Abstract

The (013)HgTe layer growth of different thicknesses by molecular beam epitaxy on complex substrates (013)CdTe/ZnTe/GaAs, with the precision control of composition and thickness by the ellipsometric method in situ, is presented in this article. The growth temperature was ∼180 °C. The HgTe layer thickness ranged from 7 to 1300 nm. Measurements of the azimuthal dependence of reflected second harmonic generation signals and the null method revealed stresses in the HgTe layers. The maximum stress of ∼123 MPa was observed in HgTe layers with a thickness from 80 up to 120 nm, which was determined as a critical thickness. At high thicknesses, the stress relaxation, which has an inversely proportional dependence on thickness, was observed. The residual stress was ∼10 MPa at the HgTe thickness of 1300 nm.