Structural and optical properties of 1.3 μm wavelength tensile-strained InGaAsP multiquantum wells grown by metalorganic molecular beam epitaxy

Abstract

Tensile strained 0.5%–1.8% InGaAsP multiquantum wells (MQWs) grown by metalorganic molecular beam epitaxy are comprehensively characterized by using transmission electron microscopy (TEM), x-ray, photoluminescence (PL), lifetime, photocurrent, and absorption measurements. Cross-sectional and plan-view TEM photos reveal that, irrespective of the strain values, the tensile strained well layers have flat surfaces in the growth direction and consist of fine parallelepipeds laterally. Optimizing the strain compensation conditions, i.e., keeping the net strain less than 0.3%, makes it possible to grow high optical quality MQWs with 1.8%-strained well layers. As the well strain increases from 0.5% to 1.45%, however, the PL intensities of the misfit-dislocation-free MQWs monotonically decrease and the minority carrier lifetime decreases from 1.4 to 0.9 nsec. The laser threshold current density decreased with increasing well strain in the 0.5%–1.3% range, decreased to 0.6 kA/cm2 at 1.3% and slightly increased in the 1.45%–1.8% range.