Overcoming the pseudomorphic critical thickness limit using compliant substrates

Abstract
We demonstrated the high‐quality molecular beam epitaxy growth of exceedingly thick In0.14Ga0.86As pseudomorphic layers on thin, free‐standing, compliant GaAs substrates. We first fabricated 800‐Å‐thick compliant platforms before growing a lattice‐mismatched layer on the platform. The layer we grew exceeds its usual critical thickness by about twenty times without strain relaxation. X‐ray analysis confirms a shift in the InGaAs peaks grown on the compliant substrate, indicating an unrelaxed strain of 0.9%. Moreover, atomic force microscope profiles verify that layers grown on compliant substrates are much smoother than layers grown on a plain substrate.